I've worked in the mental health sector of a hospital for years and no one believes me.
I was working at a State Hospital, which was very old, and falling apart, despite the administration's best efforts. The money just wasn't there anymore.
I was working in the Forensic Management Unit, which is where mental health patients who are involved in the legal system are kept, either pending trial or post-trial mental-health confinement. The rest were transient from other units from the facility. The State Hospital was built in 1892 as the State Asylum. Back then, there were Steam Tunnels that ran between the different buildings on the campus. They had steam pipes running through them, connecting the buildings to the central boiler, but that's not nearly all. There were small 'cells' running the length of the steam tunnels, and each of them, according to the 20-year-old photographs that were passed around in my orientation class, had strange ring-bolts set into the concrete.
Our instructor said that was from when the old asylum was overcrowded back in the 1920's and 1930's. They would store the overflow down in these tunnels, chained to the floor. These tunnels would reportedly get to about 150 degrees when the boiler was on, with little airflow. The State eventually, in the 1980's, closed these tunnels and had their entrances concreted over save for small ventilation grates, dotted around the campus. It had one elevator access, which required a key that only the unit manager and facility director supposedly had. This elevator was housed in the Forensic Management Unit.
I had occasion to use that elevator once, without any choice. I was waiting to go upstairs, where I worked the midnight shift, and used the elevator. Instead of grinding and squeaking its way up to the second story, it groaned its way down. When the elevator finally stopped, I was already nervous, but what the heck, right?
The elevator doors opened and I beheld a long, dark hallway, lit with one, white light. Shadows collected around it like aberrant party-goers. Thankfully, the doors almost immediately began to close, and I breathed a sigh of relief. The doors were nearly closed... As someone stepped into the circle of light.