In the decades following the Civil War, thousands of people assembled in Arlington National Cemetery’s James R. Tanner Amphitheater to honor the fallen soldiers each May on Decoration Day (which we now call Memorial Day). By the early 20th century, the event had grown so popular that Congress agreed to build a new, larger arena in its place: the Memorial Amphitheater.

When President Woodrow Wilson laid the cornerstone on October 13, 1915, it contained a copper box with documents and mementos that captured the spirit of the era. Though the contents weren’t kept a secret, you can now actually see them for yourself—on May 15, 2020, Arlington National Cemetery celebrated the centennial of the amphitheater’s dedication ceremony by opening the time capsule and displaying them in a virtual exhibit.

Inside the box was one of each coin used in 1915; uncirculated stamps bearing images of George Washington and Benjamin Franklin; an autographed photo of Wilson; a Bible signed by amphitheater architect Thomas Hastings; the dedication ceremony program; directories of both Congress and Washington D.C. residents; Civil War veterans’ pamphlets; four issues of local newspapers, including The Washington Post and The Washington Times; copies of the Declaration of Independence and the Constitution; an American flag; and a map of Pierre Charles L’Enfant’s blueprints for building the city.

As Smithsonian.com reports, a few of those documents became outdated soon after being sealed in the box. The 1915 version of the Constitution had 17 amendments, but two new ones had been passed by the end of 1920: the 18th, prohibiting alcohol, and the 19th, giving women the right to vote. The American flag, on the other hand, was already inaccurate when it went into the time capsule. Though Arizona and New Mexico had both been annexed in 1912, bringing the state total to 48, the flag only included 46 stars.

Some of the items were wrapped in red tape, a seemingly insignificant detail that Archivist of the United States David S. Ferriero found especially exciting.

“All of the records in the National Archives, when they were moved into that building, were carefully protected with wrappings that were held together with this red tape,” he said in a statement. “This is where the saying comes (from) about cutting through the red tape. It is actually—literally—the red tape.”

For the last few decades, the copper box shared its hollow cornerstone abode with another, less official time capsule: A Peter Pan-brand peanut butter jar, stuffed with business cards and other notes. The box had been relocated to the National Archives while the amphitheater underwent repairs in 1974, and the workers snuck the jar into the hollow when replacing it during the 1990s.

“It was sort of a rush job,” conservator Caitlin Smith told The Washington Post. “But you can understand the impulse to add your name to history.”

You can learn more about the history of the Memorial Amphitheater and discover more about the exhibit here.

[h/t Smithsonian.com]