Here is the basic study, with measured drawings, photographs, and written description, of a major monument in Iran, the ruins of Sarvistan, which has been much discussed but up to now has been poorly documented and is thus little known. The author examined the ruins of all buildings which had been attributed over the years to the Sasanians, Iran's last pre-Islamic dynasty (A.D. 226-651), concentrating on the impressive remains of a building near the town of Sarvistan, 100 km southeast of Shiraz. Sarvistan, considered a key monument of Persian architecture since its "discovery" in the 19th century, occupies a prominent place in the history of medieval architecture of both East and West.