Originally, one entered the Ħal Saflieni Hypogeum through a structure at ground level. Criterion (iii): The Ħal Saflieni Hypogeum is a unique monument of exceptional value. IntegrityThe Ħal Saflieni Hypogeum is one of the best preserved and most extensive environments that have survived from the Neolithic. The Ħal Saflieni Hypogeum has also yielded several important artefacts of great artistic significance. The Ħal Saflieni Hypogeum is protected by a buffer zone, and both the Ħal Saflieni Hypogeum and its buffer zone are formally designated by the Malta Environment and Planning Authority as a Grade A archaeological site, which means they are subject to wide-ranging restrictions of building development.