There was a church here before this one. In 1849, a small wooden building was inaugurated on the shore between the Balat and Fener neighborhoods, using a house donated by the Bulgarian-Greek statesman Stefan Bogoridi, reorganized as a place of worship. It became an important gathering point for the Bulgarian National Revival — the movement for Bulgarian cultural and ecclesiastical independence from the Greek-dominated Phanar Patriarchate. The Ottoman royal decree of February 28, 1870, establishing the Bulgarian Exarchate and granting Bulgarians an autonomous Orthodox church, was first read aloud in this wooden church. It was a moment of singular importance for Bulgarian national history: the decree that effectively created the institutional framework of the modern Bulgarian nation was proclaimed here, on the banks of the Golden Horn, in a modest wooden building that would eventually burn down.

When the wooden church was lost to fire, the community faced a practical problem: the ground was too wet and unstable for heavy stone construction. The solution was a structural iron frame, a technology that was, by the 1890s, well understood — the Eiffel Tower had been completed in 1889. The architect chosen was Hovsep Aznavur, an Ottoman Armenian working in Istanbul. An international competition to produce the prefabricated cast iron components was won by the Austrian firm R. Ph. Waagner. Between 1893 and 1896, Waagner's workshop in Vienna fabricated the 500 tons of iron elements — wall panels, columns, arches, domes, decorative flourishes — and then the pieces were loaded onto ships. They traveled down the Danube to the Black Sea and then south through the Bosporus to Istanbul. After a year and a half of assembly, the church was complete. On September 8, 1898, Exarch Joseph I inaugurated it. Every piece is attached to every other piece by nuts, bolts, rivets, or welding. The building has no mortar.

Standing inside, the surprise is how warm it feels. Cast iron is not a material most people associate with sacred architecture — it suggests factories, bridges, railway stations, the pragmatic infrastructure of the industrial age. But the Bulgarian St. Stephen Church is proof that iron can be made to sing. The building is a three-domed cross-shaped basilica; the altar faces the Golden Horn. A 40-meter belfry rises above the narthex, housing six bells cast in Yaroslavl. The interior carries an elaborate iconostasis, and the decorative language is confidently Neo-Byzantine, with Neo-Baroque details woven in. The chromatic effect of the iron exterior — intricate surface patterns that stone could have produced but at far greater cost and weight — shows what the material, in skilled hands, can achieve. St. Stephen belongs to a small 19th-century tradition of iron churches: the British, who patented corrugated iron in 1829, exported portable iron churches to their colonies. Gustave Eiffel designed iron churches sent to the Philippines and Peru. St. Stephen outlasted most of them.

By the early 21st century, the church needed serious attention. A restoration project began in 2011 under Bulgarian-Turkish cooperation and cost more than 15 million euros. The scale of international commitment the project attracted says something about the building's symbolic weight: in 2018, on the occasion of the church's 120th anniversary, Turkish President Recep Tayyip Erdoğan and Bulgarian Prime Minister Boyko Borisov attended the inauguration of the renovated church together. The dome had been gold-plated in 2010, funded by the Bulgarian community of Plovdiv. The restoration brought the structural elements back to sound condition and gave the building back its presence on the Golden Horn. The Bulgarian community in Istanbul — small today, as it has been for most of the 20th century — still worships here. The church remains the most visible monument to their long presence in this city.