The Church of the Blessed Virgin Mary, the largest brick church in the world, went through several stages of development over the period from 1343 to 1502. Its interior displays many exquisite pieces of Medieval and Baroque art, including the stone Pieta from about 1410, a copy of the Last Judgement by Hans Memling, the original canvas dating back to 1472, the astronomical clock built by Hans Düringer between 1464 and 1470 and the main altar put up between 1510 and 1517.
http://www.gdansk.pl/en/for-tourists/Tourist-Attractions,a,12042