Considered to be the best surviving grotto in Wales, the shell grotto in Pontypool Park stands on a ridge 700 ft above sea level. Constructed as a summerhouse for the Hanbury family of iron masters who owned Pontypool Park. Built from local sandstone with a conical roof, its plain exterior gives no clue as to what lies within. Set in the floor are the bones and teeth of animals set in patterns to form arcs and circles, stars, hearts and diamonds. The walls are mostly bare stone, with calcite crystals and the remains of moss, trees and other vegetation in places. The two windows contain coloured glass. The ceiling is the glory of the Grotto. It is fan vaulted, six fans rising from six pillars and in the centre of the dome large artificial stalactites hang down. The pillars and ceiling are covered with thousands of shells interspersed with minerals and real stalactites removed from local caves. A pleasant walk leads you to the grotto, an ideal spot for a picnic, with spectacular views across the Bristol Channel.