Tucked away at the north end of Napa Valley, Calistoga is known for its geothermal hot springs and mineral water, as well as its wineries. California’s first millionaire, Samuel Brannan, arrived here in the 1840s and opened a hot springs resort, hoping it would be California’s equivalent of New York’s Saratoga Springs; the city’s name derives from this inspiration. Downtown Calistoga balances old and new, with 19th-century architecture housing restaurants, shops, and spas that offer decidedly 21st-century fare and amenities. Calistoga is also home to the Old Faithful Geyser of California. The geyser erupts every 30 minutes, beginning with bubbles and steam, and then shooting 350-degree water 60 feet into the air. The scenic trails of Robert Louis Stevenson State Park, named for the Treasure Island author who spent his honeymoon here in 1880. A 5-mile trail in the park leads to the 4,339-foot summit of Mount St. Helena. Good views of the mountain can be found at the Petrified Forest, where redwood trees, buried by volcanic ash when Mount St. Helena erupted 3 million years ago, became saturated by silica and ultimately turned to stone.