[Gr. ‘underground’]. The term was used by Herodotus, for example, to refer to the underground tomb chambers of Egypt as well as the sapping tunnels of Persian siege craft. As a specifically architectural term, it can be used for the underground rooms or cellars of buildings, such as the Hypogeum of Hal Saflieni (c. 3000 bc) at Malta (anc. Pawla). Rules for their construction were given by Vitruvius (On Architecture VI.viii), but there is no single type or use for these structures. Vitruvius’ instructions can be applied equally to the extensive cryptoportici that run underneath some colonnades, particularly those of Roman fora, for example at Arles (Anc. Arelate; see Arles §1, (i)) or Thessaloniki. The function of these is uncertain, although they were ventilated and lit through openings cut into the steps of the colonnade above; they may well have been general storerooms. Underground chambers were also used for cult purposes, often oracular. Small underground crypt chambers existed in temples, such as that of ...