Takht-e-Soleiman Castle, Takab The aggregate of the Takht-e-Soleiman monument is placed on a natural high land, about 20 m. above the surrounding plain. All the structural relics have been constructed within an oval shaped rampart. The exterior rampart with 5 m. thickness, 14 m. height and outer circumference of 1,200 m. has 38 conical defense towers. The outer wall is a remnant from the Sassanian period. During the Ilkhanan reign, a new gateway had been constructed adjoined with the former southern gateway. Within the oval rampart there are two square plots, with uniaxis and different centers. In the centers of the southern square there is a lake and the northern square an ancient fire-temple respectively. Eivan-e-Khosrow is placed to the north western direction of the lake and to its southern side is Eivan-e-Garabaq-e-Khosrow. Takht-e-Soleiman was destroyed during the Roman conquest in 624 AD. In archeological surveys around the area of the fire-temple a variety of coins, tiles and a huge copper cooking vessel (a remnant of the Islamic period), have been discovered. The Soleiman prison which consists of the remnants of a pre-historic and the Medes temple is included in this aggregate. Sites such as dormant volcanoes, thermal springs and streams around Takht-e-Soleiman are worth surveying.