U.S. Capitol cornerstone deposit (1793)

On September 18, 1793, George Washington presided over a Masonic cornerstone-laying ceremony for the United States Capitol during which organizers deposited a commemorative deposit beneath the stone. Contemporary accounts and later histories record that the deposit included coins, a silver plate inscribed with details of the event, and other ceremonial items. Historians cite this deposit as an early documented example of a time-capsule-like practice tied to a major civic building in Washington, DC.