An important settlement was developed in the prehistoric period on the south coast of Thera island and close to modern Akrotiri. During the second millenium BC this Cycladic settlement was directly influenced by the Minoan civilization, so that it also showed a parallel boom of trade and navigation. In 1967 a first systematic excavation started south of Akrotiri, under the direction of Prof. Sp. Marinatos, who carried on intensively the work there until his death in 1974. Since then, the excavation has been continued under the direction of Prof. Chr. Doumas. The singular conditions under which the prehistoric settlement came to be destroyed has as a result impressive remains to have been saved and important information on the prehistoric civilization of Thera to have been preserved almost intact from natural decay and from human intervention. Although the architectural remains are in very bad condition, the fact that large parts of buildings have been preserved – in two or three stories-and the preservation of astonishing details of the buildings, often imprinted on the volcanic layer, offer to scientists a unique chance to study thoroughly a prehistoric settlement of the Cyclads. For the presentation of the settlement on Akrotiri special effort has been given to depict an the overall impression created and also to make clear the basic character of its architecture. Therefore, the relations to the Minoan architecture of Crete as well as the building details are not analyzed here. The area excavated so far covers approximately 10.000 square meters and is 100 m. away from the sea. The buildings, streets and squares that have been so far uncovered are only part of a large settlement of until now unknown, as yet, boundaries and dimensions. Thus, the information supplied mainly for the town-planning is deficient and probably not representative of the settlement. In any case, the basic characteristics of this part of the settlement are directly noticed by anyone who visits the excavation. The well-preserved facades of the one and two-storey edifices that flank the streets together with the absence of courtyards are characteristic of how densely built the settlement was. The frequent alternation of levels on the facades with projections and recesses form complicated outlines which affect and correspond to the street formation: certain parts are narrow, others wide, some even wider and form paved squares. Two groups of buildings can be distinguished on the basis of building techniques and interior arrangement: a) buildings with stone walls and wooden reinforcements, b) large elaborate buildings with walls dressed with turf.