Belgradkapı is a quarter in Zeytinburnu district of Istanbul, Turkey. Name of the neighborhood means Belgrade Gate in Turkish, and was named so after the Ottoman sultan Suleiman the Magnificent conquered Belgrade in 1521, modern capital of Serbia, and resettled its population to several locations in Istanbul, including the present Belgradkapı area.
After conquering Belgrade in 1521, sultan Suleiman the Magnificent resettled town's population. He relocated several groups to Constantinople itself, in areas which became known as Belgrade Forest and Belgrade Gate (Belgrad Ormanı and Belgradkapı, respectively).
Following the usual pattern of the day, ethnic groups were specialized in certain crafts and jobs. Inhabitants of Belgrade Forest worked on maintenance of the freshwater reservoirs in the forest. The water was then transferred via aqueducts to downtown. There are no surviving records on the specialization of the residents of Belgradkapı, but based on the surviving artifacts and memorials from that period, they were probably in the business of leather crafting.
In general, except for few Orthodox churches ("mostly built to be inconspicuous, hidden behind high walls"), there aren't other physical remainders of Belgraders who lived in Istanbul. The subject wasn't much studied by Serbian scientists, especially not since the 1950s, so the fate of Belgrade population is unknown: were all of them assimilated, or some survived and moved back to Serbia after independence in the early 19th century. It also remains unknown why one group was settled outside of the city walls (Belgrade Forest) and other inside (Belgrade Gate).