What to put in a time capsule - a complete list
The time capsule sealed inside a cornerstone is a message sent to people who have not been born yet. When the building is one day renovated or demolished, someone will open it - and whatever you chose to enclose becomes the only direct voice from the day the foundations were laid.
This guide is a practical checklist. It walks through what belongs inside a capsule for a cornerstone laying ceremony, what should never go in, and how to seal everything so the contents survive a century or more in concrete and stone.
The essentials every cornerstone capsule should contain
A handful of items appears in almost every cornerstone capsule because each one tells future readers something specific: who built this, when, and why. Start with these and build outward from there.
Treat the list below as the core. It documents the project, the moment, and the people, which is exactly what a future generation will want to understand.
- The foundation act (akt erekcyjny) - a signed, dated document naming the investor, the building, and the people present at the ceremony.
- Current newspapers - a national daily and a local title from the day of the ceremony, capturing the wider world at that moment.
- Current coins and banknotes - a small set of circulating currency, ideally the lowest and a representative higher denomination.
- Plans and renderings of the building - printed on a durable medium so the design intent is preserved.
- A list of participants - the investor, architect, contractor, officials, and guests who attended.
- A letter to future generations - a short message addressed to whoever opens the capsule.
Documents, plans and renderings worth preserving
Paper is the weakest part of any capsule, yet it carries the most meaning. The trick is to choose what to include and then protect it properly so the words and images are still legible decades later.
Wherever possible, print on acid-free, archival-grade paper, or reproduce key documents on a more durable medium. Renderings and floor plans help a future viewer picture the building as it was first imagined, even if it has since changed.
- The signed foundation act on archival paper.
- A floor plan, elevation, or rendering of the completed design.
- A brief written history of the investor or the institution behind the project.
- Photographs of the site before construction and of the ceremony itself.
- A printed roster of everyone involved, with their roles.
Mementoes and personal touches
Beyond the formal record, a capsule comes alive through small, human objects. These are the details that make a future reader smile and feel a genuine connection to the people who stood on the site that day.
Keep mementoes flat, dry, and non-perishable. A few thoughtfully chosen items carry more weight than a crowded box.
- A commemorative coin, medal, or token made for the occasion.
- A company or institutional emblem, pin, or stamp.
- Handwritten signatures or short notes from key participants.
- A small printed photograph of the team or community.
- A symbolic item tied to the building's future purpose.
What NOT to include - and how to seal for 100+ years
What you leave out matters as much as what you put in. The single greatest threat to a buried capsule is moisture, followed by anything that can decay, corrode, or react chemically with its neighbours over time.
Sealing is the other half of the job. A capsule is only as good as the barrier keeping air and water away from its contents, so plan the container and the closure as carefully as the contents themselves.
- Avoid: food, plant matter, or anything organic that will rot.
- Avoid: liquids, gels, or items with any moisture in them.
- Avoid: untreated metals or batteries that corrode and leak.
- Avoid: ordinary plastics and inks that degrade or stick together.
- Seal: use a watertight, non-corroding container such as stainless steel, sealed glass, or a purpose-made capsule.
- Seal: enclose a desiccant sachet to absorb residual humidity.
- Seal: protect paper in archival sleeves and close the container so it is airtight and watertight before it is set into the cornerstone.
Frequently asked questions
What is the most important item to put in a time capsule?+
The foundation act. This signed, dated document names the building, the investor, and the people present, and it is the single record that explains to a future reader exactly what was being commemorated and by whom.
Why should I avoid putting food or liquids in a capsule?+
Anything organic or moist will decay inside a sealed container and the resulting damp and chemical reactions can destroy everything else. Moisture is the number one enemy of a long-buried capsule, so keep the contents completely dry and non-perishable.
How do I seal a time capsule to last 100 years or more?+
Use a watertight, non-corroding container such as stainless steel or sealed glass, add a desiccant to absorb humidity, protect paper in archival sleeves, and close the container so it is fully airtight and watertight before it is set into the cornerstone.
Can I have a capsule and ceremony arranged for our project?+
Yes. We organise complete cornerstone laying ceremonies across Poland, including the capsule, the foundation act, and the sealing. Scope and content are tailored to each project and priced individually.
Planning a cornerstone laying ceremony?
Tell us about your investment - we will prepare a run-of-show and a quote tailored to your construction site.