Piastów is a town in central Poland, near Warsaw, with 23,331 inhabitants. It is situated in the Masovian Voivodship ; previously, it was in Warsz…Piastów is a town in central Poland, near Warsaw, with 23,331 inhabitants. It is situated in the Masovian Voivodship ; previously, it was in Warszawa Voivodship. With 3963 persons/km², it is the second most densely populated township in Poland.