1. Fairfield Hills State Hospital, Newtown, Connecticut

Fairfield Hills State Hospital opened in Newtown, Connecticut in 1931 to help alleviate some of the state’s overpopulation issues in its other mental institutions. The facility was constructed across 770 acres and its 16 buildings were all connected by underground tunnels.

The tunnels were mainly used to transport patients between treatments and laboratories, confinement rooms, operating rooms, and in the unfortunate cases, the morgue.

At its peak, the hospital could contain 4,000 patients, but the ratio of patient-to-doctor had always been an issue with the facility.

The grounds were partially redeveloped in 2009, long after its closing in 1995. Some of the buildings are being used as offices or for commercial use, but many remain untouched since its last residents were moved to other facilities. Open to the public, exploration of the grounds is highly encouraged, although any vacant buildings are off limits.

With many out-of-operation hospitals being either renovated or demolished, the number of abandoned buildings left to explore are slowly dwindling, making now as good of a time as any to experience them while they’re still here.

Next, check out 10 of NYC’s Abandoned Hospitals and Asylums, or Inside NYC’s Abandoned Paramount Theater on Staten Island. Get in touch with the author on Instagram @mjohnathonrich.