<P> Every temple rested on a masonry base called the crepidoma, generally of three steps, of which the upper one which carried the columns was the stylobate . Masonry walls were employed for temples from about 600 BC onwards . Masonry of all types was used for ancient Greek buildings, including rubble, but the finest ashlar masonry was usually employed for temple walls, in regular courses and large sizes to minimise the joints . The blocks were rough hewn and hauled from quarries to be cut and bedded very precisely, with mortar hardly ever being used . Blocks, particularly those of columns and parts of the building bearing loads were sometimes fixed in place or reinforced with iron clamps, dowels and rods of wood, bronze or iron fixed in lead to minimise corrosion . </P> <P> Door and window openings were spanned with a lintel, which in a stone building limited the possible width of the opening . The distance between columns was similarly affected by the nature of the lintel, columns on the exterior of buildings and carrying stone lintels being closer together than those on the interior, which carried wooden lintels . Door and window openings narrowed towards the top . Temples were constructed without windows, the light to the naos entering through the door . It has been suggested that some temples were lit from openings in the roof . A door of the Ionic Order at the Erechtheion (17 feet high and 7.5 feet wide at the top) retains many of its features intact, including mouldings, and an entablature supported on console brackets . (See Architectural Decoration, below) </P> <P> The widest span of a temple roof was across the cella, or internal space . In a large building, this space contains columns to support the roof, the architectural form being known as hypostyle . It appears that, although the architecture of ancient Greece was initially of wooden construction, the early builders did not have the concept of the diagonal truss as a stabilising member . This is evidenced by the nature of temple construction in the 6th century BC, where the rows of columns supporting the roof the cella rise higher than the outer walls, unnecessary if roof trusses are employed as an integral part of the wooden roof . The indication is that initially all the rafters were supported directly by the entablature, walls and hypostyle, rather than on a trussed wooden frame, which came into use in Greek architecture only in the 3rd century BC . </P> <P> Ancient Greek buildings of timber, clay and plaster construction were probably roofed with thatch . With the rise of stone architecture came the appearance of fired ceramic roof tiles . These early roof tiles showed an S - shape, with the pan and cover tile forming one piece . They were much larger than modern roof tiles, being up to 90 cm (35.43 in) long, 70 cm (27.56 in) wide, 3--4 cm (1.18--1.57 in) thick and weighing around 30 kg (66 lb) apiece . Only stone walls, which were replacing the earlier mudbrick and wood walls, were strong enough to support the weight of a tiled roof . </P>

What were some characteristics of greek architecture and art