The Hypogeum also known as Hal Saflieni, is an underground temple dating back to the Copper Age between 4000 BC and 2500 BC. It is a cultural asset of outstanding prehistoric importance. It is the only known example of a subterranean structure of the Bronze Age. It is situated at Paola in Hal Saflieni Street. There are three levels underneath each other.
It was discovered by accident in 1902 by a stone mason who was building the foundations of some houses. Immediately the Museums Department of the time took action where they discovered a wealth of archaeological material.
In recent times the houses above this monument have been removed and a small exhibition and audio-visual show is presented to visitors before they actually enter the site. It is to be noted that the glass wall that surrounds the upper level is a type, which protects the site from certain climate changes that might occur as the years go by.
The upper level is a burial complex where rock was dug out to form burial chambers. Here, remains of more than 7,000 human bones were discovered. The bodies were burried with various ornaments. Stone implements, flint tools, stone, alabaster and clay statuettes, and a great variety of personal ornaments like shell beads and precious stones were found
The middle level consists of various chambers very smoothly finished, which give the impression of built masonry. The workmanship is all the more impressive when it is considered that the chambers were meticulously carved using only flint and stone tools. Impressive spiral paintings in red ochre are still visible in some areas.
One of the niches in the 'Oracle Chamber' has the characteristic of echoing deep sounds. The carved facade is magnificent and the quality of its architecture is in a remarkable state of preservation.
The chamber known as the Holy of Holies is a huge sculptured area, which looks very much like the megalithic temples built above the ground.
The Hypogeum is on one of UNESCO underground heritage sites.