In mainland greece there is nothing comparable to the Early Helladic (EH) Corridor Houses during this period. All that has been discovered are villages or modest agglomerations (O. Polychronopoulou, in Darcque and Treuil 1990, 473–84). Houses lack regular plans, and the apsidal house type is the most common in the Peloponnese and central Greece, though also encountered in Thessaly. Mudbrick is used as a matter of course. The architectural tradition is different in the Cyclades, where houses of rectangular plan are often built entirely of stone, which is easy to come by in the islands. On the main sites (Haghia Irini, Phylakopi) the houses are more tightly grouped and regularly planned than on the mainland.