The Church of SS. Paolo e Domenico (now Arap Camii or the “Arab Mosque”) is a converted Gothic church in Galata. It originally was used Dominicans living in Genoese Galata in the 14th century.
Spolia used in and around the building indicate existence of a Byzantine building in the area. It is possibly the location of a 6th-century church named of Hagia Eirene. The eastern passageway has several marble architectural fragments, including a marble arcosolium piece similar to those in Chora. The western wall of the passageway and its marble architectural fragments are Byzantine, possibly dating to the Early Byzantine era. According to Ottoman sources, a mosque was built here during the general Maslamah’s siege of Constantinople in 717. While there is no evidence to support this legend, later treaties make it clear that there was in fact a mosque in Constantinople. 
During the Latin occupation of Constantinople (1204-1261), a small church dedicated to St. Paul was probably built here. Evidence of this church comes from gravestones found in the area. Between 1323 and 1337, the Dominicans built a monastery near this church, which was dedicated to St. Dominic. The monastery seems to have included a chapel dedicated to St. Paul, by whose name it was also called. Pope Gregory XII issued an indulgence for the maintenance of the church in 1407. Around 1475 or a little after, the church was converted into a mosque by Sultan Mehmet II and called Galata Mosque. In 1492, Arabs from Andalusia were settled in the neighborhood of this mosque, which subsequently became known as the Arab Mosque (Turkish Arap Camii).
The church was a three-aisled basilica, built in the Italian Gothic style. It is not a typical Gothic church, as it is constructed of bricks and stone, probably due to the employment of local masons. Two rows of marble columns separated the nave from the aisles. It had a squared-off apse and flanking chapels and lacked a narthex. The nave was covered by wooden roof, which was higher than the roofs above the two aisles. The apse rose higher than the side aisles and is covered by a groin vault. It originally had lancet windows, and evidence also of a rose window, which is now blocked off. The current minaret, located on its southeastern corner of the building, was originally a belfry. It is possible several funerary chapels used by Genoese families were next to the northeaster n aisle.
The building underwent several renovations during the Ottoman period. It was first restored by Mehmed III (1595–1603). Restorations made by Saliha Sultan, mother of Mahmud I, following the Galata fire of 1731, significantly altered the church, replacing Gothic elements with Ottoman windows and portals. It was also restored twice in the 19th century after two fires. In 1913, its entire roof was removed and rebuilt, and its galleries were also rebuilt with wooden columns. Genoese tombstones with inscriptions and family coats-of-arms and traces of frescoes in the bema were discovered during this restoration. It was also recently restored.