http://www.historyworld.net/wrldhis/plaintexthistories.asp?paragraphid=dor

Buildings first started in Greek cities on the coast of Turkey around 200 BC when cement became a structure material. Before cement, people were using gypsum plaster (used in Egypt) or bitumen (in Mesopotamia) to construct their buildings. The Romans used ground volcanic lava in place of clay, Their cement is the strongest mortar in history until the development of Portland cement. There are three architectural forms from the 1st century BC: The Dome, The Temples, and The Arch. All these form of buildings shared a common thing of concrete.