The intersection (Harvard and 2nd), at which you will find the Post Office, is kind of the Civic center of the city. The Post Office is located on the southeast corner, the Public Library on the northeast, and City Hall (where I took these two photos) at the northwest corner. A block to the south, along Harvard, is the Depot and the Claremont Bikestation, and to the east, along 2nd are the Colleges, but for whatever reason, this intersection just does not seem to be as bike-busy as some of the others in town.
The United States Post Office building in Claremont was built in 1936 as a project of the Works Progress Administration. As mentioned above it is one of the cornerstones of Claremont's civic center. Be sure to check out the mural by Milford Zornes, in the lobby, which depicts scenes of Claremont from the 1930s. The building's Spanish Colonial Revival architectural style matches the City Hall building located diagonally across the intersection.
This post seems to have some legs, spiked some interest with people, so I am going to provide a little update here. First is a link to Claremont Heritage and a written description of the Zornes mural in the Post Office lobby. It provides a good panel by panel look at the work, and a little bit about Zornes. Second a link to the Flicker photostream of courthouselover. The mural wraps around the entire lobby interior, along the upper portion of the walls, making it difficult to photograph. If you jump to the photostream, the images are pretty good considering. The mural is just one of those things best viewed in person.