Hagia Sophia was a Byzantine church in the Thracian city of  Bizye (modern Vize, Turkey). Now known as Ayasofya (Gazi Süleyman Pasha) Mosque, it is located in Turkish Thrace on the southwestern foothills of the Strandzha (Istranca) Mountains . Bizye, a place of exile during the early Byzantine period, was the home and cult center of St. Mary the Younger, a pious woman of Armenian origin who died there in 902 and was subsequently buried in the city’s cathedral. 
The Byzantine church is situated within the confines of the fortification walls on the southwestern slopes of the acropolis of Bizye. Both its size and commanding presence overlooking the Thracian plain seem to indicate that this church located on the city’s acropolis was once the city’s principal place of worship, presumably Bizye’s cathedral. It might be related to the period of Byzantine expansion in the Balkans in the late eighth and ninth centuries, which is very poorly represented in terms of architectural monuments. It is similar in design to Hagia Eirene in Constantinople. It has a basilical plan on the ground level, the gallery includes a cross-domed unit, with barrel vaults bracing a dome approximately 6 meters in diameter, raised above a windowed drum. The corner compartments are isolated on the gallery level, not unlike the considerably later churches of Mystras. Minor vaults are an admixture of groin vaults, domical vaults, and barrel vaults. An arcosolium in the south aisle appears to be original. The church was originally built of alternating bands of brick and stone, but this had been much repaired in rough stonework. Built above the remains of an older basilica, the foundations are exposed to the east.
However, the date of the cathedral’s dedication during the Byzantine period remains unknown. The Life of Saint Mary the Younger does not refer to it by name,  and while the building’s modern Turkish name Ayasofya Mosque may well preserve the memory of a previous Byzantine dedication, the present association with Holy Wisdom cannot be traced back further than the nineteenth century. It is unclear which Suleyman Pasha it is named after. 
Bizye was first captured by the Ottomans in 1368 but later returned to Byzantine rule (probably in 1411). It is possible that the church was converted into a mosque once Bizye was captured again by the Ottomans in 1453. While there are no written documents that would help to elucidate the history of structural modifications and restorations in Ottoman times, the building seems to have served as the city’s principal mosque well into the twentieth century.