Photo credit: jkb
The Hypogeum in Ħal-Saflieni, Paola, Malta, is a subterranean structure excavated c. 2500 B.C. Thought to be originally a sanctuary, it became a necropolis in prehistoric times. It is the only prehistoric underground temple in the world. The Hypogeum was depicted on a 2 cents 5 mils stamp issued in the Maltese Islands in 1980 to commemorate the acceptance by UNESCO of this unique structure in the World Heritage Site list.