The mosque is popularly known as the Blue Mosque for the blue tiles adorning the walls of its interior. Like many other mosques, it also comprises a tomb of the founder, a madrasah and a hospice. When Ahmed I (reigned 1603-1617) ascended the throne, no imperial mosque had been built in the city for 44 years. The Sultan selected Mehmed Aga as chief architect and picked a site of immense symbolic significance, in the heart of the city on a site containing the ruins of the Byzantine Great Palace and facing the Hippodrome to the west. With its six minarets and its semi-domes cascading on four axes, the mosque represents the ultimate evolution of the imperial Ottoman mosque.