litlanesfoss Iceland

Columnar jointed volcanics exists on many places on earth. Perhaps the most famous basalt flow in the world is the Giant's Causeway on the northern coast of Ireland, in which the vertical joints form polygonal columns and give the impression of having been artificially constructed.
An ancient 13th century religious complex, called Nan Madol, was built on the Pacific island of Pohnpei, using columnar basalt quarried from various locations on the island. The massive ruins remain to this day.