Babylonian temples are massive structures of crude brick, supported by buttresses, the rain being carried off by drains. One such drain at Ur was made of lead. The use of brick led to the early development of the pilaster and column, and of frescoes and enamelled tiles. The walls were brilliantly coloured, and sometimes plated with zinc or gold, as well as with tiles. Painted terracotta cones for torches were also embedded in the plaster. Assyria, imitating Babylonian architecture, also built its palaces and temples of brick, even when stone was the natural building material of the country - faithfully preserving the brick platform, necessary in the marshy soil of Babylonia, but little needed in the north.