Hypogeum of Ħal Saflieni - Credit: Wikimedia Commons
The Hypogeum of Ħal Saflieni () is a Neolithic subterranean structure dating to the Saflieni phase (3300 – 3000 BC) in Maltese prehistory, located in Paola, Malta. It is often simply referred to as the Hypogeum (), literally meaning "underground" in Greek. The Hypogeum is thought to have been a sanctuary and necropolis, with the estimated remains of more than 7,000 people documented by archeologists, and is among the best preserved examples of the Maltese temple building culture that also produced the Megalithic Temples and Xagħra Stone Circle. Read more on Wikipedia
Source: en.wikipedia.org