I didn't do it. Its not an active mint and I'm not certain of how or when they do tours. The top one is a different location for the mint, the original mint. Its in China Town of SF.
A look inside the 75-year-old new mint for its anniversary last week: http://haighteration.com/2012/05/inside-the-u-s-mint-part-two.html (And neither are in Chinatown. The old mint is in Soma, the new mint is in the Castro.) EDIT: Didn't even know about the first mint! That one is kind of in Chinatown, kind of in the Financial District.