Built by Studio Piano in Pomezia Italy, this barrel vault consisted of fiberglass panels in a moveable structure. The panels were taken down from one end and added to the other as the mining process moved down the line. As the FRP panels did not degrade under the fumes caused by the sulfur extraction process, and were lightweight enough to to be easily moved, it was the ideal material for this specialized structure. Each panel weighed only 14 kg, and was translucent enough to allow sunlight to the interior. Photos copyright Renzo Piano Building Workshop.