 A church building is inherently conservative, and except for the extraordinary intervention, changed very slowly. A large proportion of churches had been founded by at least the late 12th century, many appearing in the Doomsday census of 1089. Elements from these early buildings often survive in the doorways or the base of towers, showing typical rounded arches and massive walls of the Norman style. Additions over time could include a reconstructed window, a new baptismal font, a tomb sculpture, or a series of carved wooden choir stalls for the clergy, attesting to differing eras of piety and style. (Stanbury and Raguin 2009, Other Internet Resources)