Constructed in the 1930s, the hot mineral therapy pool was regarded, much like by the native Wappo Indians and later guests, as having spiritual, healing, and rejuvenating properties. Guests soothed what ailed them by taking private baths in custom-made bathing stalls that included a bathtub. A pipe extending from the capped well to the pool helped regulate water temperatures. The pool's walls are made of lava rocks indigenous to the area, and structures like this were thought to protect the water's magical healing qualities while also containing the water and keeping out garbage and debris from trees and plants. Today, hot mineral therapy pools at some local Calistoga hotels and resorts reach temperatures of more than 150°F/60°C.