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 guesstimated 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. History The Hypogeum was discovered by accident in 1902 when workers cutting cisterns for a new housing development broke through its roof. The workers tried to hide the temple at first, but eventually it was found. The study of the structure was first conducted by Manuel Magri, who directed the excavations on behalf of the Museums Committee, starting from November 1903. During the excavations, a portion of the contents of the Hypogeum, including grave goods and human remains, were emptied out and discarded without being properly catalogued. To confound things further, Magri died in 1907 while conducting missionary work in Tunisia and his report on the Hypogeum was lost. Excavation continued under Sir Themistocles Zammit, who attempted to salvage what he could. Zammit began publishing a series of reports in 1910 and continued excavating until 1911, depositing his findings at the National Museum of Archaeology in Valletta. The Hypogeum was first opened to visitors in 1908 while the excavations were ongoing. The four contemporary houses built on the site of the hypogeum were demolished to build a museum. Further excavations took place between 1990 and 1993 by Anthony Pace, Nathaniel Cutajar and Reuben Grima. The Hypogeum was then closed to visitors between 1991 and 2000 for restoration works and to arrange it for visits; and since its reopening, Heritage Malta (the government body that looks after historical sites) allows entry to only 80 people per day, while the site's microclimate is strictly regulated. In 2011, a more intensive program was launched to monitor the decay of the site. Scientific research on the Hypogeum is ongoing, and in 2014, an international team of scientists visited to study acoustics. The Hypogeum reopened in May 2017 after closing for a year to improve its environmental management system. Description Later archeological excavations indicate there was once a surface shrine that marked the entrance to the Hypogeum, with