In many churches, the basement is reserved for social activities: quilting circles, play groups, donuts and coffee after Sunday services. At Center Church on the Green in New Haven, Connecticut, it’s reserved for the dead.

In the early 1800s, the town of New Haven decided they needed a new meeting house. Though the plot of land they chose was already occupied by hundreds of tombstones dating back to the 1600s, officials were undeterred. Taking care not to disturb the final resting places of the deceased pioneers, builders created an enclosed chamber around the burial ground, then erected the building right on top.

Not all of the dead got such VIP treatment, however. The headstones that weren’t directly in the footprint of the new church remained outside, but a few years later, the city decided to use that part of the cemetery for green space. Though the stones were removed, the people weren’t—it’s estimated that thousands of corpses are still resting beneath New Haven Green, the park surrounding the church.

The stones lucky enough to make the cut are still in the basement of Center Church today, which is known as the Crypt. Because they haven’t been exposed to the elements for centuries, many of them are remarkably well-preserved. Notable residents include Margaret Arnold, the wife of infamous traitor Benedict Arnold (he remarried after her death and is buried in London); James Pierpont, a founder of Yale University; and some of the family of 19th president Rutherford B. Hayes. Although the original dirt of the cemetery was once paved over with cement in 1879, it has since been replaced with brick, which allows for better water circulation. (Still, the tombstones have suffered from some water-related deterioration, and the church is raising money for their preservation.)

The Crypt is open for tours on Saturdays from 11 a.m. to 1 p.m. from April through October.

All photos above: Regina Buenaobra via Flickr // CC BY-NC 2.0