Rayen Castle belongs to Sasanid Era and it is located on a hill on the southeast of current Rayen in Kerman. Rayen Castle with an area of over 22000 m² is the second adobe building in the world after Bam Citadel. The plan of Rayen Castle is almost square around which there is a wall to the height of over 10 meters. The only entrance of this castle is located to the east side. This entrance has a great and magnificent propylaeum. Various parts of Rayen Castle include the alcove, royal houses, public neighborhoods, fire-temple, bazaar and four storehouses.