Over the two centuries since the White House was first occupied by John Adams in 1800, the building has undergone numerous changes and improvements. Many of the souvenirs and pieces in collections and museums have originated, for the most part, from the three major renovations. In 1902 Teddy Roosevelt remodeled the whole ground level to update and “modernize” it. President Coolidge replaced the roof and added to the third floor in 1927. Harry Truman, in the early 1950s, completely gutted and rebuilt the White House to correct major structural safety issues.