Tus Citadel
The Citadel of Tus is a Sasanian era citadel, located in Tus, Razavi Khorasan province, Iran.
It is made of brick and is rectangular in shape, having four circular towers at each corner, with two more circular towers in the inner structure. Not much remains of the structure; however, its size is comparable to other large citadels of the Sasanian era.