German police have detained a person after a major fire broke out at the Kehlsteinhaus, a Nazi-era mountain guest house known as the Eagle’s Nest, in Bavaria on Friday night. The fire swept through the building near Berchtesgaden, close to the Austrian border. Around 200 firefighters and other emergency personnel were deployed, but the guest house’s location, 1,834 meters above sea level, complicated their efforts. Police said nobody was believed to have been inside when the fire broke out. The cause remains undetermined, although German media have raised the possibility of arson. Completed in 1938, the Kehlsteinhaus hosted Nazi officials and their guests. Adolf Hitler rarely visited the site, which became a mountain restaurant in 1952. Another former Nazi complex, Hitler’s Wolf’s Lair headquarters in Poland, remains open to visitors. According to the Kehlsteinhaus’s account, Hitler made just 14 documented visits.