Establishing (Government) and planning them are considered of the first architectural works that accompanied the spread of Islam in and out of the Arabian Peninsula. Thusthey became one of the most significant axes of planning the Islamic city and expanding its architectures. As it was first planning the mosque and then establishing office at a neighbor place in the city centre at a distinct and fortified locations. It has taken its name (castle of Government) since the early Islamic era and it has been known as (Qasr Al-Emarah) since the era of the 2nd caliph Omar bin Al-Khattab to be a followed as tradition at all cities and countries as a result of the Islamic Liberations and that expanded to free YemenLevant and Egypt besides all Iraqi citiesespecially Mosul city (the subject matter) in which establishing and planning them drew a great attention since the beginning of the Islamic liberation in (16 A. H. 637A. D.) at the era of Omar bin Al-Khattab who establishedin whichthe first at the Islamic era was near the mosque on the hill of Qulaiaat over looking at Tigris. It witnessed a considerable development in its architectures and the style of their planning during the following Islamic eras. Thus its role increased greater and its area expanded. Its name diversified with its locations. In whichhouses and palaces were established to perform the functions and tasks of office of government which took the characteristic and name of the palace (Qassr). Its remains are still observed with its unique location at the west bank of Tigrisat the eastern north of old Mosul city near the old castle of Mosul (Bashttabya) and shrine of Imam Hassan. The political and administrative role of this castle increased during the Arab and Islamic eras to represent the house of the governor (Wali)his familyentourage and relatives beside being the official headquarter of state administrationrecords and staff of all civilpolitical and military tasks. Its role increased after the fall of Arab caliphate and the appearance of foreign governmentsespecially at the era of Ottoman state.