This is an archway in Kalemegdan Park on the other side of which is a wooden bridge. You can see its railing on the left!
Photo that reminds me of windows/walls I have seen on back streets of some Italian cities I’ve visited. Once again, these windows come to you courtesy of Belgrade’s adjacent municipality of Zemun.
This cheery lemon-colored wall I found in Zemun, one of Belgrade’s adjacent municipalities. Nice, healthy-looking cacti, too!