Many people know Hart Island as the home of the almost impossible to access Potter’s Field, where the homeless and people whose families could not afford burials are buried in a public unmarked graveyard. But the island was also home to a Phoenix House rehab facility, as well as a women's asylum called the Pavilion. Remnants of the island’s more animated days remain, with letters and hospital beds strewn throughout the crumbling buildings. There has been a push to get the island opened up to the public; some city officials have even advocated for a Governors Island-like park.

This 20-acre island, off the Bronx in the East River, dates back to the 1880s and served as a quarantine site famously known for housing Typhoid Mary. The hospital was converted to an experimental drug rehab center in the 1950s but the program ended in 1963, due to corruption and high costs. The NYC Parks Department has controlled North Brother Island since 2001, however the abandoned hospital still stands and while it is off-limits to the public (and difficult to get to), people still find their ways. Currently, the city is exploring the possibilities of making the island accessible to the public.

On Roosevelt Island, the decrepit 19th century Gothic Revival structure that once functioned as the Renwick Smallpox Hospital is high on the list of city’s creepiest landmarks. The hospital opened in 1856 in an effort to keep those with smallpox separated from the rest of society, and treated roughly 7,000 patients throughout its 19-year run. The hospital was later converted into a nursing school but eventually the building was shuttered and has fallen into disrepair. There have been talks of renovating and reviving the structure, but some Roosevelt Island resident would rather just see it torn down.

It’s been 35 years since the Greenpoint Hospital shuttered and ever since, plans to redevelop the building into affordable housing have been continuously stalled. It’s become home to squatters in the years since it was closed.

Built in the 19th century, the crumbling Brooklyn Navy Yard Hospital is one of the few original buildings that remain at the Navy Yard; many of the buildings that once surrounded it, including the ramshackle townhouses of Admiral’s Row, have since been torn down. Steiner Studios is planning to transform the space into a media complex but for now, the eery structure, which once treated soldiers during World War II, remains in a dilapidated state.

While most people head to Ellis Island to see its main building, or as part of their trips to see the Statue of Liberty, there is another historic site that’s much more difficult to access. The 29-building complex dates back to 1902 when the Ellis Island Immigrant Hospital was opened as the country’s first public health hospital. The hospital quarantined thousands of immigrants with infectious diseases who were deemed too sick to enter the country. But many people weren’t treated—those who died at the hospital were sent to the campus’s morgue. By the 1930s, the hospital was on a decline and eventually shuttered. By 1954, the complex was officially abandoned and is now accessible through a select number of private tours.

While Staten’s Bayley Seton Hospital is still up and running, eight of the twelve buildings located on the 20-acre Stapleton campus have been abandoned—so it’s hella creepy here. In the 19th century, the site was home to the Marine Hospital Service and the Seaman’s Retreat, before going on to be renamed several times and eventually selling to the Salvation Army in 2008. The campus has been used as the filming scene for several episodes of the television show Gotham.