The historical sources (549 B.C.) introduce Hegmataneh or Hamadan of the Islamic period as one of the oldest cities and perhaps the first city founded by the Iranian ethnic groups. There is no doubt that part of this fame is due to the attribution of this city to the Medes and the first Iranian dynasty. The archeological activities to discover the works of Medes’ Hegmataneh has a record of a hundred year. However, these activities have not lead to the discovery of works in this city. This issue besides other ambiguities which has been formed on the presence of the great kingdom of the Medes has perplexed the researches on Medes; without no doubt, access to any kind of data on the capital city of Medes can provide better understanding of the political structure and the nature of Medes government.Efforts have been made through field studies and analysis of existing documents to present reliable documents on the capital city of the Medes, its LOCATING and structure and lack of discovery of works in that city. The existing documents leave no room left for any doubt about the presence of Medes government and its capital city and they confirm the agreement of its place with the present Hamadan city. On the other side, documents show that all sovereignty centers and castles were built on the hills and defendable heights and the housing area of the ordinary people were formed near them. Since the present Hegmataneh hill had been formed in Ashkanid age an on a natural bedground, and as Pisa hill is in lack of works of Medes age, so the only possible option is Mosala hill. Based on the existing documents, since Ashkanid period up to Qajar period, this place was the place for the establishment of the city castle. The remains of such a castle has remained up to recent decades on the hills surfaces based on writings and air photos. Based on this, the place of settlement of ordinary people can be located at the place of the old texture of the city with the centrality of the Jam-e mosque.