STOCKHOLM — A hatch on a Swedish church tower inadvertently left open for three decades resulted in 2 tons of pigeon droppings amassing in the tower.

The church’s property manager said the layer of droppings was 12 inches deep when it was discovered during a May inspection of the Heliga Trefaldighets Kyrka in Gavle, 105 miles north of Stockholm.

Lennart Helzenius said on Thursday that church staff had been shocked by the sheer number of bags of excrement cleaners were removing from the tower. He said the droppings filled 80 bags in the first round of cleaning, and then just as many in the second round.

Helzenius said the hatch had probably been left open since the 1980s.