The highest mountain in the area and in fact in all of Napa County, topping at over 4,300 feet, Mt. St. Helena is made of uplifted volcanic rocks, formed over 2.4 million years ago. While the center of volcanic activity has moved north, signs of it remain in the hot springs that bubble up around the area.Russian traders from Fort Ross were the first to climb the mountain in 1841, naming it after Princess Helena de Gagarin. Today, its still popular with hikers who can see as far away as San Francisco and Mt. Shasta on a clear day.