This building belongs to the late Zand and the early Qajar eras and is known under different names, including Arg Hesam al-Dole, Bibi Arus Castle and Arg-e-Sarkar.
This monument is generally different from other buildings of the city in terms of architectural design.The Arg’s architecture is hexagonal and ends in a mesmerizingly beautiful white, cone-shaped at the top.
Built in a Ziggurat style, the building has six floors. The ground floor features the best architectural plan of all. The Arg’s entrance, built ahead of the ground floor, features a few beautiful arches.
Two floors of the building are large and usable, while the other floors were designed to supplement the exterior facade, which is decorated magnificent architectural ornaments with mud, brick, lime and mortar on the dome of howz space. According to older documents, the courtyard and the garden were originally in Chaharbagh style, later losing their original design after a series of modifications.