and the use of rectangular rooms with walls of
sun-dried mud-brick and mud-plastered roofs
supported by wooden beams appear in the Hassunan,
Samarran, and Ubaid periods perhaps as
early as 6000 BCE. Building techniques were normally
quite simple. Mesopotamian builders
knew how to build arches and vaults and at times
used freestanding or attached columns, although
flat roofs supported on timber beams were most
common.
Several examples ofbuilding plans have been
found on clay tablets, showing that Mesopotamian
buildings were often carefully designed
and that measured plans were often used in their
construction. A seated statue of Gudea, ruler of
Lagash (circa ZlOO), is depicted with such a plan
together with a scale ruler on his knee. Evidence
from Persepolis (circa 5(0) suggests that the palaces
were laid out using a fixed metrological
system. Such a system has not been demonstrated
with certainty for earlier periods but it
is very likely that this was the case. On the other
hand, it is less likely that either geometric or
numerical theories exercised great influence on
Mesopotamian architects.