An international team of scientists is about to descend on Malta’s Hypogeum of Hal Saflieni, a UNESCO World Heritage Site which is believed to be the oldest prehistoric underground temple in the world. The subterranean structure is shrouded in mystery, from the discovery of elongated skulls to stories of paranormal phenomena. But the characteristic that is attracting experts from around the globe is the unique acoustic properties found within the underground chambers of the Hypogeum.