Piusa Caves were created in 1922 as a quarry of quartz sand that was used to make glass. It was quarried underground. Besides the old mining caves there are also three man-made caves in the south from the quarry. The purpose of the caves were geological observations. Piusa caves have evolved into a popular site for hibernating bats. It is the largest known hibernation colony in Eastern Europe. It is possible to visit the caves with a guide and via the visitor centre. There is a 1.4 km hiking trail which begins just near the caves.