Founded in 1535, the Casa de Moneda (House of Money) in Mexico City is the oldest Mint in the New World. Since 1991 the Mint has been striking one Troy ounce 99.9% silver Libertads. The 2009 Libertad shows the ten different coats of arms used on Mexican coins over the years. The obverse shows winged Liberty overlooking Mexico City and the distinctive "oM" mintmark.