Dareh Shahr or Darrehshahr is located in southeastern Ilam Province 840 kilometers from Tehran enjoying a mild climate. It is situated in a relatively wide valley with many historical ascent and descents. Attacks of Arabs and Assyrians caused destruction of the city. Its forgotten and extinct fire-temple is still standing. Dareh Shahr may be the same city of Madakto the Elamite capital. The name of the city comes from 'Darreh' meaning 'valley' and 'Shahr' meaning 'city'.
In the ancient time Elamites were the governor of Lurestan mountains and constructed several strong buildings. Dareh Shahr was the first Elamite city attacked and destroyed by Assyrians in addition to the massacre of people.
There are in Simareh Valley the remains of the Sassanide monuments, hence Dareh Shahr might has been a thriving city in the Sassanide and the Parthian periods. In the ruins of Dareh Shahr, belonging to the Sassanide era, there are the vestiges of crosses, alleys and passages with a specific order of urban development criteria of that time.
All the buildings of Dareh Shahr are constructed from abraded rubble stones and gypsum. Abundance of gypsum in Seimareh Valley from one hand, and simplicity of working with it have caused to making the best use of this material in the Sassanide architecture. The coins discovered in this area belong to Khosrow III and his successors. Holding vast fertile lands, different and rich water resources, rich pastures, dense forests, Dareh Shahr is one of important and ancient cities of Ilam province.