Have you ever seen a stone engraved with "定礎" (cornerstone) installed on a building, apartment complex, or school?
While most people have seen one at some point, not many actually know what a cornerstone is.
So today, we'll reveal the many hidden secrets of the cornerstone.
We'll uncover fascinating mysteries about cornerstones, including why they exist and their history.
In the latter half, we'll also cover what's inside a cornerstone box, so if you're curious, be sure to read to the end.
What Is a Cornerstone?
Cornerstones are found not only on recently constructed buildings, but on older structures as well.
They have a long history and are said to carry various meanings.
Before diving deeper into cornerstones, let's start with how the word is read.
How Do You Read It?
Among the kanji commonly seen in Japan, there are many cases where the correct reading is unclear or people end up mispronouncing them.
The word "定礎" is one such example.
Some people read it as "jōseki" or "jōso," but the correct reading is "teiso."
Since it's a word rarely encountered in daily life, it's perfectly understandable that some people can't read it.
This word "teiso" carries the following meaning.
The Meaning of a Cornerstone
As the characters suggest, "teiso" means "to set the foundation stone."
A foundation stone refers to the base stone placed beneath a pillar, or the stone upon which a building is constructed — and "teiso" means to establish that stone.
However, from the explanation above alone, few people would understand why a cornerstone is installed.
Fundamentally, a foundation stone also carries the meaning of "the core of something" — an essential element.
Just as one might say "The prince became the cornerstone supporting the nation," the word "teiso" can be used in contexts beyond architecture.
However, in ancient times, it was impossible to construct a building without first laying what was called a foundation stone (soseki) into the ground.
This was because standing pillars directly in the ground would cause them to absorb moisture from rain and snow-soaked soil.
Wooden building materials are weak against moisture, which causes them to deteriorate faster or rot entirely.
In addition, building materials in direct contact with the ground are easily eaten by termites and animals, so construction was impossible without foundation stones.
For these reasons, cornerstones became a fixture in the construction industry, used to establish the position of the foundation stones that serve as the base for a building's pillars.
Installed in Many Different Places
Cornerstones are found not only in high-rise buildings and apartment complexes, but in a wide variety of locations.
There are no rules specifying which buildings must have a cornerstone — schools, childcare facilities, care homes, and commercial establishments all may have them.
In terms of placement, it is common to position them near the main entrance or on the southeast side of the building.
The reason for the southeast is that it is considered the entrance of great fortune, and many buildings and facilities have their entrances facing southeast.
Because cornerstones appear in so many places, many people assume they are mandatory.
However, there is no rule requiring every building to have one.
They continue to be installed today simply as a longstanding tradition carried over from the past.
The Stones and Designs Used for Cornerstones Vary Widely
There are many different types of cornerstone plaques engraved with "定礎."
If you look closely at buildings, you may find cases where "the design was so original I didn't notice it" or "I never would have thought that was a cornerstone" — it's surprisingly easy to miss them.
Let's start by introducing some typical examples of cornerstones.
The color of a cornerstone plaque is typically black, gray, or brown stone.
White stone is also used to match certain buildings, making the design quite flexible.
The text is generally engraved, and Mincho (serif) typeface is the most common style.
A characteristic feature is that color is rarely added to the engraved text, which can make the lettering hard to see depending on the stone color.
Brown stone in particular tends to make the text less visible.
Also, when engraving text, a small date is often carved below the main "cornerstone" inscription.
The date engraved was most often the day construction began, but today it may also reflect the date of the cornerstone-laying ceremony.
Dates vary — some use the Western calendar, some the Japanese imperial calendar with just the month, and others include the full day.
Nowadays, cornerstones that break free from these traditional conventions have become more common, featuring rich and creative designs.
There are all kinds of distinctive cornerstone plaques: ones engraved with a company's philosophy or a motto, ones with "teiso" written in hiragana, fancy and charming tiles designed with flowers or stars, and more.
Recently, sleek stainless steel cornerstones have become popular, and some don't even include the word "teiso" at all, making them harder to spot — but hunting for different cornerstones around town is itself an attraction.
There are many enthusiasts who love cornerstones.
For such fans, a city filled with buildings, apartments, and various facilities must feel like a treasure trove.
Installing a cornerstone both demonstrates the solid foundation of a building and reflects an era where design-forward cornerstones that match the building's aesthetic are a priority.
So how did the cornerstone become rooted in Japan's architectural culture? What are its origins?
The Origins of the Cornerstone: How Did the Culture Come About?
Because cornerstone plaques are typically engraved in Mincho typeface, it's easy to assume that the practice of embedding a cornerstone plaque is uniquely Japanese — but that's not the case.
Its roots can be traced back approximately 5,000 years to the Mesopotamian civilization, when stone construction flourished.
At that time, the cornerstone served as a reference point when beginning construction.
This role evolved during the later periods of ancient Greece and ancient Rome, where a stone marking the foundation of a building would be installed at the start of construction along with prayers for the building to be completed without incident.
In those eras, foundation stones made of corrosion-resistant materials such as lead and stone were embedded to reinforce the structure.
From the time of ancient Greece and Rome, the wish for the building to stand long without collapsing was also embedded in the cornerstone, and that spirit continues to be carried forward today.
In Japan, the practice of the cornerstone began during the Meiji era.
As Japan transitioned from the Edo to Meiji period, the country opened its doors to the world and European culture rapidly permeated Japanese society.
As the nation pursued modernization and many Western-style buildings were constructed, Western architectural engineers were brought in not only for design but also for supervision, and the cornerstone culture spread through them.
Incidentally, the oldest known cornerstone in Japan was discovered at the Kanazawa Castle ruins.
It is inscribed with "Hōreki 13, Mizunoto-Hitsuji year, Kuwahajime, 25th day of the 6th month," and has been identified as dating to 1763, the mid-Edo period.
It is believed to be a cornerstone installed before the practice became widely adopted in Japan, making it extremely valuable.
Whether the date marks the day construction began or the day the cornerstone ceremony was held remains unknown.
Today, it has become common practice to install the cornerstone plaque at the completion of construction.
Originally, embedding a cornerstone box at the base of the pillars during foundation work was established practice in Japan as well.
Furthermore, while cornerstones were often placed at the southeast corner of a building, today they are most commonly installed near the building's entrance.
As times have changed, the conditions for installing a cornerstone have also evolved, but in any era, the ceremony to pray for construction safety — the "cornerstone ceremony" — remains indispensable.
Next, let's explain the cornerstone ceremony.
What Is the Purpose of the Cornerstone Ceremony?
The cornerstone ceremony is a ritual held to pray for the safe completion of construction and the longevity of the building, but its form has changed over time.
The Cornerstone Ceremony Today
With modern construction methods, wood is no longer used as the building's foundation, nor are foundation stones used to protect pillars.
Because corrosion-resistant metal materials are used, the practical necessity of the cornerstone itself has diminished.
However, the wish for safe construction completion and a long-lasting building lives on.
The cornerstone ceremony today is often held not at the start of construction, but when the building is nearing completion or has been completed.
It has also come to serve as a ceremony celebrating the near-completion or completion of the building.
As a result, it has begun to blur together with other construction ceremonies, and the content of the ritual itself has become less clearly defined.
Various Ceremonies in the Construction Industry: How Do They Differ from the Cornerstone Ceremony?
The construction industry holds many ceremonies — before construction begins, during construction, and after the building is complete.
Here we'll introduce the various ceremonies in the construction industry while highlighting how they differ from the cornerstone ceremony.
・Ground-Breaking Ceremony (Jichinsai)
First, the ground-breaking ceremony is an essential ritual performed before construction begins.
It involves reporting to the deities that a new building will be constructed on the land, as well as settling the spirits of the land's gods, purifying the site, and praying for construction safety and divine protection.
・Roof-Raising Ceremony (Jōtōshiki)
The roof-raising ceremony is held partway through construction.
For wooden structures, it is celebrated at the moment the final piece of timber is placed in the framework; for steel-framed structures, the ceremony involves lifting the steel frame with a crane.
For reinforced concrete structures, it is held when the final concrete pour of the structural body is made — the details differ depending on the building materials used.
In all cases, the ceremony gives thanks for the safe completion of the framework and prays for continued construction safety.
For residential buildings, it is characteristic for the property owner to treat the construction workers to food and drinks, or to give them gifts and gratuities as a gesture of appreciation.
・Completion Ceremony (Shunkōshiki)
The completion ceremony, also known as the "Shunkō Hōkokusai," is a ritual in which the gods are informed that construction has been safely completed.
The cornerstone ceremony is often held before the completion ceremony.
・Completion Reception (Shunkō Hirō)
The completion reception is a celebratory gathering to express gratitude and thanks to those who contributed to the construction.
The program includes congratulatory speeches, greetings, and the presentation of certificates of appreciation. While the completion ceremony centers on religious rites, this event tends to serve as a gesture of appreciation for those involved and as a PR opportunity.
The Contents of the Cornerstone Ceremony
Now let's look more closely at what takes place during the cornerstone ceremony.
Before the cornerstone plaque is embedded into the building — the main event of the cornerstone ceremony — a purification ritual is performed and prayers are offered for safe construction and the building's longevity.
On this occasion, a Shinto priest is invited from a shrine to conduct the following rituals:
Temizu no Gi (Purification of Hands): A ritual for the Shinto priest to purify themselves before entering the site
Shūbatsu no Gi (Purification Rite): A ritual to purify the bodies and minds of the attendees
Kōjin no Gi (Summoning of the Deity): A ritual to welcome the deity to the purified altar
Kensen no Gi (Offering): A ritual to present offerings to the welcomed deity
Norito Sōjō (Recitation of Prayers): A ritual in which prayers and words of celebration are offered to the deities
Kirinusa Sanmai (Purification Scattering): The scattering of sacred sake, rice, and salt offered at the altar to the four directions of the land as a purification rite
After these rituals, the ceremony proceeds to the cornerstone rite.
In the cornerstone rite, first the "Jiho Doku" (reading of the cornerstone declaration) is performed, praying to the deity for the building's longevity.
Next, the curtain covering the cornerstone is lifted, and in the "Cornerstone Plaque Setting Rite," the plaque is embedded into its designated location.
During embedding, the "Imigote no Gi" (sacred trowel rite) is performed by pouring mortar into the space where the cornerstone will rest, followed by the "Soseki Suetsuke no Gi" (foundation stone placement rite) in which the cornerstone is set in place.
After confirming that the cornerstone is level and vertical, the "Imitsuchi no Gi" (sacred mallet rite) is performed to announce the completion of the cornerstone installation.
Additionally, the ceremony includes the "Tamagushi Hōten" (sacred branch offering), praying for the stability of the land and protection of the owner and construction workers; the "Shōjin no Gi" (departure of the deity), performed as the deity departs the altar; and the "Shinshu Haitai" (sharing of sacred sake), in which the sacred sake offered at the altar is distributed among the attendees.
What Is Inside a Cornerstone Box?
While cornerstones themselves are less commonly seen today, a cornerstone box is sometimes embedded alongside the cornerstone when it is installed in a building.
The cornerstone is set into the wall of a building as a stone plaque, and the cornerstone box is buried behind it.
The box is often made of copper or stainless steel for their corrosion resistance, though wooden boxes are also sometimes used.
The practice of using cornerstone boxes is said to have begun around the end of the Meiji era.
Until then, only the cornerstone plaque was installed during the cornerstone ceremony, but by including a cornerstone box, it became possible to preserve a record of the time when the building was constructed.
The contents of a cornerstone box vary depending on the building.
・A charm from the local shrine
・Building blueprints
・A nameplate bearing the names of the owner and construction team
・Photos taken during construction
・A newspaper from the day of the cornerstone ceremony
・Weekly magazines popular at the time
・Coins and banknotes in circulation at the time
・Popular toys and merchandise of the era
There are no specific requirements for what goes inside a cornerstone box, and since it is used like a time capsule, most items placed inside reflect everyday life at the time of construction.
While cornerstone boxes are most commonly found in large structures like office buildings and factories, they have increasingly been embedded in private single-family homes as well.
The contents of residential cornerstone boxes typically include the home's construction blueprints, newspapers and magazines from the time of construction, and commemorative family photos.
The cornerstone box is not opened until the building is demolished, making it a wonderfully romantic artifact.
For larger buildings, the box may remain sealed for a very long time, making even the mere presence of items from the time of construction a historically significant treasure.
Even today, when a cornerstone and its box are discovered during the demolition of a historic building, the event is significant enough to make the news.
This shows just how historically valuable a cornerstone box — which offers a window into the past — truly is.
Examples of Cornerstone Box Openings
Cornerstone boxes have been retrieved from the demolition of many buildings over the years, revealing mementos and historically precious items placed inside at the time of construction.
In some cases, valuable materials previously unknown to researchers have been discovered, demonstrating that cornerstone boxes hold immense significance in the history of Japanese architecture.
In the greater Tokyo area and other major cities, large buildings rise alongside the ongoing demolition and reconstruction of older ones.
With buildings being torn down and rebuilt somewhere every day, a cornerstone box may be discovered and opened somewhere even as you read this.
Here, we introduce four notable examples of cornerstone box openings from across Japan.
Cornerstone Box Opened at Prefectural Office Building No. 5 in Miyazaki City
During house-moving (hikiya) work being carried out on Prefectural Office Building No. 5 in Miyazaki City, a wooden cornerstone box was discovered.
Prefectural Office Building No. 5 itself is a highly significant piece of modern architecture, originally constructed as the headquarters of the former Miyazaki Agricultural and Industrial Bank.
After the prefecture acquired it, the building was used as the Prefectural Document Center, but as a new prefectural disaster management headquarters was to be built on the same site, a house-moving operation was carried out to preserve the historic structure for future generations.
Built in 1926, nearly 100 years ago, the building's historical significance made the discovery of valuable materials inside a major news story.
The cornerstone box was embedded behind the outer wall bearing the engraved word "teiso," and was made of paulownia wood measuring 23cm wide × 29cm long × 9cm tall.
Inside were a silver commemorative plaque made for the cornerstone laying, a copy of the Nisshū Shimbun newspaper dated April 8, 1926 — the date the cornerstone ceremony is believed to have been held — and seven coins in circulation at the time.
Each item conveys a piece of life as it was during the building's construction, and all hold great value as historical records.
The contents of this cornerstone box, opened after 91 years, can now be viewed free of charge at the Prefectural Document Center.
It is open to the public, so if you're interested, please do visit and let your imagination take you back to Miyazaki City as it was at the time of construction.
Cornerstone Box Discovered at the Former IBM Japan Headquarters
The former IBM Japan headquarters was located in Roppongi, and when it was demolished due to redevelopment, the cornerstone plaque was removed and a cornerstone box was found behind it.
The former IBM Japan headquarters building was completed in 1971 and remained in use until the company relocated its headquarters to Hakozaki.
At the time of its completion, the building attracted considerable attention as a highly innovative structure, featuring a column-free interior and an energy-efficient design.
The cornerstone box discovered was made of copper and had been tightly sealed.
When it was opened, the items on top were three newspapers: a general daily newspaper, an English-language newspaper, and a construction industry publication.
Notably, the construction industry paper featured a major article introducing the former headquarters building, demonstrating the enormous attention it received as an architectural achievement.
Other contents included the building's blueprints, a new employee recruitment guide, a building brochure, completion photographs, and a brass nameplate listing the names of related parties in both Japanese and English.
The blueprints bore the signature of the late Shōji Hayashi, a celebrated architect, and included the seal of Kunihiro Misu — then designing the building and now chairman of the Japan Federation of Architects & Building Engineers Associations — making it an extraordinarily valuable historical find.
The existence of the cornerstone box was little known even among IBM Japan employees who worked in the building, reportedly causing surprise within the company.
The contents were scheduled to be displayed within the company, so they may be viewable at the current headquarters.
Additionally, a video from the time of the former IBM Japan headquarters building's completion has survived and was made available to view on YouTube.
Such video footage is rare, so we encourage you to at least watch it and get a feel for what things were like back then.
Cornerstone Box Discovered During the University of Tokyo New Library Project
As part of the University of Tokyo's new library project, construction work was underway in the plaza in front of the General Library to build a new wing featuring an automated underground storage system capable of holding 3 million books, along with a Library Plaza for interdisciplinary exchange.
Within the construction site lay the brick foundations of the old library, which had been founded in 1892 during the Meiji era and destroyed in the Great Kanto Earthquake.
While the brick foundations — previously identified through buried cultural property surveys — were being demolished, a metal cornerstone box was discovered.
The discovery of these brick foundations during this excavation was itself a historically significant event, and the further discovery of a cornerstone box within them made it all the more extraordinary.
Fortunately, the demolition of the brick foundations was being carried out by hand rather than by machine, which allowed for the discovery.
Although the box suffered a puncture from a demolition tool, had the work been done by machine, the box likely would have been badly damaged or might not have been found at all.
Inside the metal box, which measured approximately 10cm × 17cm, was a metal plate wrapped in an official gazette dated August 25, 1890.
The front of the metal plate recorded the completion of the Imperial University Library in 1890, and on the reverse were engraved the names and origins of the construction supervisor, Hanzō Yamaguchi, and the designer, Masamichi Kuru.
Since the designer of the Imperial University Library had previously been unidentified, this proved to be an invaluable piece of historical evidence.
Furthermore, while the practice of cornerstone boxes is said to have begun in the Meiji era, no examples had previously been discovered from Meiji-era buildings, making this a landmark find in the history of Japanese architecture.
It is currently unclear where the discovered cornerstone box is being preserved or whether it is available for public viewing, but given its extraordinary significance, it is likely being carefully stored.
Cornerstone Box Discovered During the Renewal of Osaka Electro-Communication University's Neyagawa Campus
The former Building A of Osaka Electro-Communication University's Neyagawa Campus had watched over students for 53 years since its completion in 1967.
In the autumn of 2018, large-scale renewal construction of the Neyagawa Campus began in earnest.
Before Building A was demolished, Building F — located between the OECU Innovation Square and lecture Building J — was torn down.
Subsequently, the parabolic antenna on the roof of Building T, a satellite communications research facility, was removed.
Building T is home to over 30 years of accumulated data recording weather phenomena such as rainfall and is recognized globally as a highly valuable research facility by the ITU Radiocommunication Sector.
After the phoenix palm trees — a symbol of the Neyagawa Campus — in front of Building M were purified and felled, demolition of the former Building A began.
Prior to demolition, the "electron orbit" symbol mark of the campus, mounted on the wall, was removed.
As the demolition proceeded, the cornerstone plaque was removed and the cornerstone box found behind it was retrieved.
The metal box, measuring 32cm × 15cm × 7cm and double-layered for protection, was well preserved.
From the cornerstone box that had lain dormant for 53 years inside the former Building A, completed in 1967, came a nameplate, business cards of those involved in the construction of Building A, campus construction blueprints, coins that were in circulation at the time, and copies of the Nihon Keizai Shimbun, Asahi Shimbun, and Mainichi Shimbun from the completion date.
All items are regarded as valuable historical materials.
Is It OK to Install a Cornerstone at Home?
Since cornerstones and cornerstone boxes are not widely known among the general public, few people install them in their private homes.
When installing one at home, the common practice is to embed a cornerstone plaque bearing the completion date and the owner's name in the southeast corner.
Cornerstones are typically associated with the construction of office buildings and factories as commemorative or ceremonial gestures, so they are not often used in ordinary single-family residences.
However, cornerstones and cornerstone boxes are fundamentally installed as a prayer for safe construction completion and gratitude for its successful finish, as a wish for the growth and development of the owner or company, and as a time capsule preserving the moment of completion.
Therefore, there is absolutely nothing wrong with installing a cornerstone and cornerstone box at home.
In fact, installing a cornerstone and cornerstone box as a time capsule could add a special treat for future family members.
Some people also install cornerstones and cornerstone boxes for feng shui or home orientation purposes.
Of course, examples of installing a cornerstone and cornerstone box in a private home are quite rare, but it can become a treasured keepsake that allows you to reflect on the time of construction while hoping for the building's continued wellbeing.
In modern times, a standard single-family home is generally expected to be rebuilt after 30–40 years.
After 30–40 years, the original owner is likely still alive and the next generation may have already been born.
Imagining the cornerstone box being opened together when the next generation rebuilds for a more comfortable life certainly has a romantic quality to it.
The reasons for installing a cornerstone vary from person to person, so if you want to install one, why not give it a try?
However, be aware that there are important points to consider if you ever sell a single-family home with a cornerstone installed.
The presence of a cornerstone bearing personal information could very well result in a decrease in property value.
It also means that personal information remains embedded in the property, creating the risk of potential misuse.
Since there are few precedents, it is difficult to say definitively whether the value will actually decrease — it likely varies by property — but it is important to be aware that the risk increases.
Be sure to keep that in mind when considering installation.
Summary
In this article, we covered the meaning of cornerstones, their origins and history, the reasons for holding cornerstone ceremonies, the contents of those ceremonies, what is inside cornerstone boxes, examples of cornerstone box openings, and the possibility of installing a cornerstone at home.
The cornerstone originally carried a significance somewhat akin to signaling the start of construction, but in modern times, as construction methods have changed, the practice of the cornerstone itself has become less common.
Even so, as a tradition passed down through generations, cornerstone ceremonies continue to be held today.
Behind the cornerstone, there is sometimes a cornerstone box — a kind of time capsule filled with items from the time the building was completed — and valuable historical materials are sometimes discovered inside.
In recent years, many buildings are being rebuilt for safety reasons, so you may have more opportunities to see what's inside cornerstone boxes in the news.
Also, since there is no rule prohibiting the installation of a cornerstone in a private home, it can be a meaningful gesture to install one with the spirit of a time capsule.
However, as noted above, there are points to be careful about, so if you are considering installation, consult with a construction company and proceed accordingly.
Frequently Asked Questions About Cornerstones
Q1. Is the installation of a cornerstone legally required?
There is no legal obligation to install a cornerstone. It is carried out as an architectural custom, and whether to install one is left to the discretion of the building owner.
Q2. What is inside a cornerstone box?
Typically, items such as the building's blueprints, newspapers from the time of construction, a list of those involved, and the cornerstone ceremony program are included. It also serves the role of a time capsule.
Q3. What does the date on a cornerstone signify?
The date engraved on a cornerstone typically indicates the day the "cornerstone ceremony" was held. Note that it is not the completion date or the construction start date.
