The new building, which started construction on April 1, 1869, and was completed in November, 1874, was designed by Alfred B. Mullett in a conservative Greek Revival style with a sober Doric order.

[7] The central courtyard contained a well which helped save the structure during the fire of 1906, when the heat melted the plate glass windows.

[1] "The Granite Lady" nickname is inaccurate, as most of the building is made from sandstone, quarried from Newcastle Island, British Columbia.

In 2003 the federal government sold the structure to the City of San Francisco for one dollar—an 1879 silver dollar struck at the mint— for use as a historical museum.

In 2014, the San Francisco Museum and Historical Society began raising money for the second phase, to include permanent exhibitions.

[9] In 2016 to celebrate the public re-opening, on the first weekend in March, the Old Mint hosted a "San Francisco History Days" event; more than 60 historic organizations participated.