Kalemegdan Fortress & Park

The fortress was begun by the Celts and fortified by Rome: legionary camp Flavia Singidunum guarded the confluence from the 1st century, and Roman emperors Probus and Claudius II were born in its orbit. In 1403 it became the capital castle of despot Stefan Lazarević — his Despot’s Gate of 1403–05 survives as the complex’s oldest standing structure. The Hungarians strengthened it against the Ottomans after 1427; Suleiman the Magnificent took it in 1521; and from 1688 to 1867 it changed hands ten times between Ottomans, Austrians and Serbs, each rebuilding the walls the last had breached — the Austrians adding the great Baroque bastions in 1717–1739. The Military Museum’s collection now reads the full 2,000 years; the open-air gun park includes equipment from the 1999 war.