Are tank tops ok to wear in Poland?

Above gives a good answer but one strong piece of advice regarding clothing etiquette -- better not wear the sleeveless dress to Auschwitz, or put a blouse over it. When visiting sombre sites and entering places of worship, at least your shoulders down to your knees should be covered (add head covering and more leg covering if it happens to be Orthodox or Jewish). But when you're having fun in Zakopane, wear and do whatever your good judgement says is OK (you know, the usual, treat others as you would have others treat you). Just remember to pack some layers if you plan to hike up in the Tatras even if it is 90F down in the valley -- the weather has been really crazy and you wouldn't want to be caught unprepared!  more