Overview of the village of Oia on the Island of Santorini, Greek Islands, Mediterranean. Oia village on Santorini with houses and typical blue domed churches. The architecture of Santorini is predominantly low lying cubical houses made of local stone and whitewashed or lime-washed with various volcanic ashes used as colours. Many houses have rooms carved into the rock which helps with insulation in both summer and winter. Santorini is the largest island of the circular archipelago which bears its name and is a remnant of a volcanic caldera which erupted some 3,600 years ago. Greek Islands. There are many churches in the villages on Santorini as originally each family home had its own chapel.