As the best site for crossing the Colorado River, Yuma has long been an important transport center. The Yuma Territorial Prison, with cells carved out of the rock, is Arizona’s most visited State Historic Park. From 1876 to 1909, it housed many of Arizona’s most dangerous and notorious criminals. Fort Yuma was built in 1851 during the gold rush to protect settlers and the southern route to California. The St Thomas Mission, the Quechan Indian Museum and the Yuma Crossing State Historic Park are other popular attractions.