Parks are beloved places of sanctuary, offering harried urbanites a quiet refuge for relaxation and reflection — whether in the form of a grassy field, a wooded glen, or a dusty hiking trail. Buffalo Bayou Park features a particularly novel form of this brief escape: a vast subterranean concrete cistern that once held 15 million gallons of drinking water for the people of Houston.

Built in 1926, this 87,500-square-foot (8,129-square-meter) space was one of Houston’s first underground reservoirs. The eight-inch-thick concrete roof is supported by 221 concrete pillars reaching 25 feet high that march in rows into the dim distance.

A public works facility for decades, an irreparable leak was eventually found in the structures walls and thus it was subsequently decommissioned in 2007. The city was preparing to demolish it when it was found by the partnership developing Buffalo Bayou Park. After briefly considering using it for parking or mulch storage, the developers decided to keep it as an unusual and attractive space for park visitors.

While the park added an entrance tunnel, a railed walkway around the sides, and some internal lighting, the cistern remains otherwise unchanged. A shallow layer of water remains standing on the floor to play with the shafts of sunlight admitted via ceiling hatches, and the sound insulation provided by the thick concrete sidewalls creates an absorbingly silent atmosphere while also boasting a 17-second echo (although loud noises are prohibited).

If going into a dark, enclosed underground space isn’t your thing — or if you just like interactive art installations — the Cistern can be viewed from above via the Down Periscope project created by Donald Lipski. Additionally, a 360-degree look at the Cistern can be found here. Future plans for the space include rotating light and sound art installations to showcase the unique visual and acoustic characteristics of the space.