Sinan Paşa Mosque was a Byzantine church located near the Sea Walls of the Golden Horn near Aya Kapı (Turkish the ‘Holy Gate’). Only part of its foundation survives today and its identity is uncertain. It seems to date to the Palaiologan era, though this is uncertain as well. It seems to have been either a parakklesion or a burial chapel with a long, two-story apsidal hall similar to Boğdan Palace. It was converted into a mosque by Sinan Pasha, the brother of the Grand Vizier Rüstem Pasha in the middle of the 16th century.