PAST (short for Polska Akcyjna Spólka Telefoniczna, Polish Telephone Joint-stock Company) was a Polish telephone operator in the period between World War I and World War II. It is notable for its main headquarters in Warsaw, which at the time of its construction was the first and tallest skyscraper in the Russian Empire and the tallest building of Warsaw. The fight for the building during the Warsaw Uprising of 1944 also added to the legend of the place.