The ruins of the Monastery of Stoudios, more fully Monastery of Saint John the Forerunner \"at Stoudios,\" are situated not far from the Propontis (Marmara Sea) in the section of the city called Psamathia, today\'s Koca Mustafa Paşa. The only part to survive into the 20th century was the Cathedral of St. John Baptist, probably the oldest remaining church in Istanbul, a 5th century basilica which was converted by Bayezid II\'s equerry into the mosque İmrahor Camii (literally, Mosque of the Stablemaster).