Grand vizier was the title of the effective head of government of many sovereign states in the Islamic world. It was first held by officials in the later Abbasid Caliphate. It was then held in the Ottoman Empire, the Mughal Empire, the Sokoto Caliphate, the Safavid Empire. In the Ottoman Empire, the grand vizier held the imperial seal and could convene all other viziers to attend to affairs of the state; the viziers in conference were called "Kubbealtı viziers" in reference to their meeting place, the Kubbealtı in Topkapı Palace. His offices were located at the Sublime Porte. The Prime Minister of Pakistan is referred to in Urdu as Wazir-e-azam, which translates literally to grand vizier.