Zinden gate and towers, Belgrade Fortress, Kalemegdan Park, Belgrade, Serbia, Europe

photography colour colour image color color image horizontal horizontal image outdoors outside day nobody no one no one travel destination travel destinations travel belgrade serbia europe european elevated view city cities belgrade fortress kalemegdan park tourist destination landmark landmarks famous well known well known kalemegdan zinden gate fort forts fortified fortification fortress fortresses history historical historic heritage antiquity tower archaeological site ancient civilisation