Smithsonian Castle Seismic Moat and Renovation

under construction

The Smithsonian Castle, a 170-year-old building on the National Mall in Washington, D.C., is undergoing renovation including the creation of a hidden seismic moat to protect it from earthquake damage. The moat will separate the building from the ground using base isolation technology, allowing it to ride out earthquakes without damage to its unreinforced sandstone facade. The renovation also includes mechanical, plumbing, and electrical system replacements, interior and exterior refurbishments, and basement expansion for event space and mechanical equipment. The project is scheduled to reopen temporarily in late May 2026 for the America 250 celebration and permanently in 2028.