Drilled Monoliths are unique decorative stones used as beautiful water features. Our drilled monoliths make the perfect statement piece in any outdoor space, from contemporary garden designs to commercial outdoor areas. Drilled Monoliths have a flat base and can be used on any surface and will elevate any garden design. Monoliths are millions of years old and are hand selected from the quarry in North Wales. These drilled monoliths come in grey slate, rustic slate and plum slate.