Kalenderhane Camii (Mosque) is a Beyzantine Church next to Bozdoğan (Valens) aqueduct that was turned into a mosque. Here, tha first church that dates back to 8th century achieved its final shape in 12th century in 18th century, it was turned into a msoque by Darüssaade Ağası Beşir Ağa.
At the west of Kalenderhane, it has it has two narthexes one of which is outside and the other inside. The main location of the structure with a closed cross plan is covered with dome with a high tambourine and the arms of the cross are covered with vaults. Its main apse with a plain wall did not reach today and only the marble plates have come today from the inter wall ornamentions of Byzantine period.
Its dome is ornamented with pen crafts, typically of Ottoman period and the vaults and pendantives are in brick without paint. New windows were opened in Ottoman period and the mosque achieved an even brighter atmosphere.