Renovations are scheduled to resume at the Smithsonian Institution Building, better known as the Castle, the Smithsonian’s first and oldest building on the National Mall in Washington.
The project had been temporarily paused for summer 2026 programming tied to the nation’s 250th anniversary of 1776, including the “American Aspirations” exhibition co-curated by Smithsonian Secretary Lonnie G. Bunch III. With that window closing, the work is gearing back up on what officials have described as the Castle’s first top-to-bottom overhaul in more than 50 years.
For mason contractors and restoration teams watching from the field, the biggest takeaway is that the most consequential scope is largely underground. Engineers are planning a subterranean “seismic moat” around the Castle’s perimeter, using base isolation to help untether the unreinforced masonry structure from ground movement during future earthquakes. Excavation has not begun, according to the reporting.
The caution is rooted in real damage. The Castle was cracked by the magnitude 5.8 earthquake that struck Louisa County, Virginia, in August 2011, with damage reported to interior beams and five decorative exterior turrets.
Below grade, the renovation also includes replacing mechanical, electrical, plumbing, and security systems and building an underground Central Utility Plant beneath the South Mall campus to serve both the Castle and the adjacent Arts and Industries Building. The reporting notes that moving heavy equipment below grade is intended to reduce impacts on the Castle’s historic interiors.
Material matching is another masonry-forward detail. The Castle’s red sandstone exterior is being restored, but the original Montgomery County, Maryland, quarry closed in 1901. Restoration has used salvaged sandstone from a New Jersey church that was demolished or slated for demolition to supply replacement masonry.
The revitalization is estimated at about $530 million, with completion and permanent reopening targeted for 2028.
Read the full, original article from Hoodline here.