The Izad Khast Castle is located in Izadkhast in the Fars Province, central Iran. The castle was built during the Sassanid Empire (224 to 651 AD) and functioned as fortified walled city on the ancient Silk Road that ran through central Iran. It is the second largest adobe building in the world after Arg-e Bam. The castle is built on a high bedrock overlooking the Izadkhast valley. Inside the castle walls are many narrow alleyways and passages criss-crossing through centuries old tiny houses and buildings. The castle and surrounding Izadkhast complex has been nominated to the UNESCO World Heritage Tentative List on August 9, 2007 in the Cultural category. Location The Izad-khast castle is located on the ancient Silk Road between Shiraz and Isfahan. The site is in the middle of nowhere and surrounded by a desert land. But a high singular bedrock overlooking a valley was an ideal location for the development of a fortified desert city in the middle of nowhere. The Izadkhvast castle is built on this singular bedrock that juts out to the Izadkhast valley. The valley around it functions as a natural deep trench. Castle fortification walls have been built around the bedrock, tall and almost perpendicular, ranging from 6 to 15 meters on three sides. On the fourth and shorter side of the bedrock, a 30 meter (100 feet) long trench had been dug. The trench is 4 meters across and 4 meters deep. Access to the castle was over the trench, through a small bridge and a gate. The site's natural topography and added fortifications made the castle one of the most unattainable buildings of the ancient times for robbers and enemies. On the valley below the castle bedrock are rocky fields, with a barren plateau behind. The Izadkhast caravanserai roadside inn stands alone in this valley, in the middle of a rocky field. History The history of the castle complex dates back to the pre-Islamic era of Iran. Izad-Khast is a Sassanid castle, built during the Sassanid Empire (224 to 651 AD) which ruled Persia (Iran) and many parts of the surrounding countries. It was then used, added and improved on until Qajars era (1794 to 1925). This has left works inside the castle belonging to different periods from Sassanids to Qajars with different architectural styles. The fire temple of Izad Khast Castle from the Sassanid era was turned into a mosque