Reinforced concrete, cast in place

Overall height: 17’– 13’ above grade, 4’ below; exterior diameter 12’; interior— a series of three concentric ledges approximately 8” wide with the following diameters: 10’8”, 9’4”, 8’; two sets of wooden stairs (12” riser to 8” tread) 7’ and 6’ high respectively; center shallow pit 56” square.

Originally sited at Silver Springs, PA

The concentric ledges are connected by a set of steep stairs so that one must walk around each ledge before climbing to the ledge below. The deepest level, sunk 4’ below the earth, has no connecting stairs.

Photo: Alice Aycock