From Citizendium - Reading time: 1 min

During the American Civil War, after Union occupation of Alexandria, Virginia, the Union seized the Mansion House Hotel and turned it into a hospital known as the Mansion House Hospital.[1]
The owners of the hotel built it in front of their luxurious home, the Carlyle House -- the "mansion" in the hotel's name.
The hospital was the largest Union hospital in the region, with 500 beds.[2] Most of the former hospital complex was torn down in the 1970s, when the State of Virginia wanted to build a park to surround and better highlight the Carlyle House mansion.
In 2016 PBS broadcast a miniseries, Mercy Street, set in the hospital.[1]