(pronounced i..a)  It covers the northern part of Santorini island. The population is 1,500 inhabitants at 2010. From Oia the ferry connects the island of Therassia (approx 450 inhabitants)  with  Santorini island. Along the cliff of Oia, houses have been delved into the porous volcanic rock - lavastone (left over from a large volcanic explosion more than 1500 years ago that sunk the center of the island). Parts of these houses are visible and the scenery that results from it is generally perceived as being typically Aegian style.

Oia is wellknown for its picturesque architecture, unique for its blend of relatively large, medieval Venetian-style houses  with small incave village homes,  which were the housing form of the rest of the town"s population. Other attributes of this area is the medieval fortification to protect from pirates. To this day laws protect the natural and architectural beauty of the town from modern manifestations, such as public phone cables, TV-satellite equipment and electrical wires.