The Bulgarian St Stephen Church in Istanbul is also known as the Bulgarian Iron Church.

This church belongs to the Bulgarian minority. The Bulgarian minority of the Ottoman Empire used to pray at the churches of the Fener Orthodox Patriarchy. Due to the nationalistic movements, Bulgarians were allowed to build their own church in the 19th century. First, a small wooden church was built on the shore of the Golden Horn between Balat and Fener squares (near Eyup district) where the current church is located, but later this was developed into a larger building. An iron frame was preferred to concrete reinforcement due to the weak ground conditions. The construction plans were prepared by Hovsep Aznavur , an Armenian of Istanbul origin. An international competition was conducted to produce the prefabricated parts of the church. An Austrian firm, R. Ph. Wagner, won the competition. The prefabricated parts were produced in Vienna and transported to Istanbul by ship through the Danube and the Black Sea. After one and a half years work, it was completed in 1898. The main skeleton of the church was made of steel and covered by metal boards. All the pieces were attached together with nuts, bolts, rivets or welding. The architectural styles come from the Neo-Gothic and Neo-Baroque periods.

(the image is courtesy of monkeytravel.org)