The Old Post Office, is a former building in Belgrade, modern-day Serbia. Located next to Belgrade Main railway station, it was considered to be one of the most beautiful buildings and symbols of the city. Built in Serbo-Byzantine Revival style upon plans by Momir Korunović, Post Office was mostly destroyed by Allied bombing of Yugoslavia in World War II and later reconstructed in 1947 in a functionalist style.

The Modern Serbo-Byzantine architectural style, Neo-Byzantine architectural style or Serbian national architectural style is the style in Serbian architecture which lasted from the second half of the 19th century to the first half of the 20th century. This style originated in the tradition of medieval Serbian-Byzantine school and was part of international Neo-Byzantine style.