The architectural style of the Ise shrine is known as shinmei-zukuri, characterized by extreme simplicity and antiquity: its basic principles date back to the Kofun era (250-538 C.E.). The shrine buildings use a special variant of this style called Yuitsu-shinmei-zukuri (唯一神明造?), which may not be used in the construction of any other shrine. The old shrines are dismantled and new ones built on an adjacent site to exacting specifications every 20 years at exorbitant expense, so that the buildings will be forever new and forever ancient and original. The present buildings, dating from 1993, are the 61st iteration to date and are scheduled for rebuilding in 2013.