The Hypogeum of Ħal-Saflieni is an ancient underground burial site located in Malta. Dating back to around 4000 BC, it is one of the oldest known structures in the world. The site features a series of chambers and passageways carved into the soft limestone, showcasing remarkable prehistoric architecture. This unique site was discovered in 1902 and is believed to have been used for both burial and ritual purposes. The Hypogeum contains numerous human remains and artifacts, providing valuable insights into the lives and beliefs of the ancient Maltese people. It is a UNESCO World Heritage Site, attracting visitors and researchers alike.