The Culture and Science Palace was for some years the highest building in Europe, and it's still the highest in Polland. Built between 1952 and 1955, it's 233m high. It was a present by Stalin, but Polish have always considered it a sign of Russian domination, a non-positive recall een if it has become a symbol in the city. From floor 30 viewpoint you'll get the best views from the city, so visiting it is a must. And there are usually quite interesting exhibitions too.