The Haunted Denver Firefighters Museum: Not For the Faint of Heart. In the heart of Denver’s North Capitol Hill neighborhood stands a seemingly quiet, historic building-but don’t let its calm exterior fool you. The Denver Firefighters Museum, once an active firehouse, harbors stories of bravery, tragedy, and… lingering spirits. Since opening its doors as a museum in 1978, this former firehouse has become a hotbed for paranormal activity, sending shivers down the spines of visitors and staff alike.