Belgrade's city centre is compact enough to walk — the distance from Kalemegdan fortress to the Temple of Saint Sava is about 3 km and can be covered on foot through interesting streets. For longer journeys, the city has an extensive bus and tram network run by GSP; routes are dense in the centre and fares are cheap. Taxis are plentiful and inexpensive by European standards; use the apps (Car:Go, Naxis) rather than hailing off the street to avoid inflated fares.
New Belgrade — the modernist district across the Sava — is connected by several bridges and a frequent bus service. The Museum of Yugoslavia and the splavovi (floating clubs) on the New Belgrade riverbank are the main reasons to cross. Renting a bicycle is possible and the riverbanks have some decent flat paths, though the centre itself is hilly. The main train station (Beograd Centar) is on the New Belgrade side, connected to the old city by tram.