In existence since 2900) B.C., the city of Babylon, under the rule of King Nebuchadnezzar (605-562 B.C.), had spread on both sides of the Euphrates River. It covered 500 acres. Many of the houses were three stories high whose flat roofs were buttressed with timbers packed with mud. For the poor who couldn’t afford the luxury of wood, there were circular mud-brick huts, supported by a center post, the walls packed with reeds and mud.Budding plumbers worked their ingenuity with the only available resource in unlimited supply-clay mixed with finely chopped straw. Copper was known to some extent from the beginning, while bronze was introduced about 2500 B.C. from outlying trade routes; sometimes it was alloyed with tin, sometimes with antimony. Some working in lead (anakum) was developing too at this time, as natives began to rivet, solder, hammer and anneal.