In ancient China, most architecture was wooden, including the few known arch bridges from literature and one artistic depiction in stone-carved relief.[33][34][35] Therefore, the only surviving examples of architecture from the Han Dynasty (202 BC – 220 AD) are rammed earth defensive walls and towers, ceramic roof tiles from no longer existent wooden buildings,[36][37][38] stone gate towers,[39][40] and underground brick tombs that, although featuring vaults, domes, and archways, were built with the support of the earth and were not free-standing.[41][42]