On the evening of March 6, 1865, Abraham and Mary Lincoln arrived at the Patent Office Building in Washington DC. They joined an estimated 5,000 guests who had gathered to attend the President's second inaugural ball. Construction of the building begain in 1836. It was used as a hospital during the American Civil War. It was spared from the wreckers ball in 1958 by then President Dwight Eisenhower. Today the building houses the Smithsonian National Portrait Gallery.