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

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 blue sky archaeological site the way forward diminishing perspective vanishing point perspective symmetry gateway ancient civilisation