This mint, one of four in the country, produces half the coins circulated in the US. It strikes 10 billion coins a year, producing an average of $3.5 million each day, and tends one-fourth of America's gold reserves-shipped from San Francisco in 1934 because Denver is not as vulnerable to earthquakes or wartime attacks.The elegant, five-story, granite-and-marble building (1906, James Knox Taylor) was modeled after the Medici Riccardi Palace in Florence, Italy. Displays of coins and currency, mint equipment and historic photos line visitors' galleries. Free weekday tours (20min) offer views of the stamping and counting rooms as a guide describes the process of striking, counting and bagging coinage.