Hot Lake Hotel in Hot Lake, Oregon, developed from an 1864 wooden commercial building at a thermal spring into a major resort, hospital, and early geothermal-heated building. Long used by Native Americans and recorded in 1812 during Robert Stuart’s Astor Expedition, the site expanded after the railroad arrived and gained national prominence in the early 1900s. Under Dr. W.T. Phy, it promoted the springs’ healing powers and became known as Hot Lake Sanitorium. A 1934 fire and later decline led to abandonment in 1991, but restoration after 2003 returned the surviving brick building to use as a hot springs resort.