Another expat in Belgrade, Andrew L., posted this in a local group, wondering what the P.U.B. stands for, since it does not look like a pub! I was curious, too, since I have often noticed the P.U.B but have been more interested in t he wooden dome above and behind it. A reader answered about the P.U.B., that it is an acronym for a long-gone Czech bank.
As for the dome, it is much more part of the building than it looks, but what EXACTLY it is, I cannot find. It was used in part of a 1967 Yugoslav film entitled "The Case of the Missing Switchboard Operator" starring Eva Ras.
