The district of Tophane (arsenal) to the north-east, opposite the point where the Bosphorus flows into the Sea of Marmora, still shares in the maritime activities later obtained permission to own a mosque or at least a house where they could hold their religious services it was more probably in Constantinople itself.

* Tophane image
This building is almost certainly the former Byzantine Church of Saint Paul which was assigned to the Dominicans in 1232 during the Latin rule in Constantinople. They rebuilt it almost completely and erected a belfry that is still there today. The church remained in the hands of the Dominicans until 1453. Shortly after the capture of the city, Mohammed II transformed it into a mosque which was assigned to the Moslems who had been driven from Spain.
In the course of restoration work in 1913 the Dominican paving and tomb stones were discovered; they have been put into the Museum of Antiquities. Most of the present building dates from the Dominican period; only a few features have survived in the western part, near the passage; the Ottoman part consists of the south wall.