"Bisutun" is the name of a cliff rising above an old caravan path, which was also a military route from Baghdad and Babylon to Hamadan, a city in northwest Iran. The town of Bisutun is located along this trail, thirty-two kilometers east of Kermanshah.
Only recently rediscovered, the old Bisutun caravanserai actually lay under the town, which had been built atop it. The caravanserai itself was constructed from the ruins of a Sasanian-era building called the "Palace of Khosrow." A nearby fortress (and most likely the caravanserai) is said to have been built by a Kurdish prince, Hasanuya. A Buyid inscription plaque, made of the same stone as the fortress, was found near the caravanserai.
Mention of the old caravanserai appears in several travelers' diaries and memoirs. In 1598, Abel Pincon, secretary for the British ambassador to Shah Abbas I (Safavid, reg. 1571-1629) refers to the caravanserai. Pietro Della Valle stayed there in 1618, and Jean de Thevenot wrote of it in 1664.
As evident from the small mosque that was located in the center of the caravanserai's courtyard, this caravanserai belongs to the early Islamic period. It is the oldest Iranian example of the (later Anatolian) typology of a mosque located in a caravanserai courtyard. It is possible that this construction was a fortified military outpost being converted to a caravanserai.
The old caravanserai was built by attaching walls to the surrounding walls of the earlier Sasanian construction. Square in plan and centered around a courtyard, it measured 80 meters per side. The main entrance was located on the east wall, which was supported on both sides by three projecting buttresses, each measuring eighty centimeters. A second entrance on the west side was three meters wide. A series of eight rectangular rooms surrounded the courtyard on each side. On eastern, northern and southern sides of the courtyard, each iwan was adjoined by two rooms, and on the western side, a small iwan fronted each room.
The mosque structure in the caravanserai courtyard was a ten by ten meter square, oriented toward Mecca. Within, it measured six square meters, and its entrance was one hundred and ten centimeters wide.
The walls of this Buyid caravanserai are approximately two meters thick. The front wall consisted of massive stone blocks, which are eighty centimeters high, and of which little remains. The caravanserai walls are composed of rubble stone from the floor to the spring line of the arches, and of brick thereafter.
During the Safavid period, a new caravanserai was constructed to its south; the Safavid caravanserai used some stone from the Buyid structure.