St. Mary's Church, or formally the Basilica of the Assumption of the Blessed Virgin Mary, is a Brick Gothic Catholic church located in central Gdańsk, Poland. With its volume between 185,000 m3 and 190,000 m3 it is currently one of the two or three largest brick churches in the world. Only San Petronio Basilica in Bologna, comprising 258,000 m3 is larger, Munich Frauenkirche and Ulm Minster also comprise 185,000 to 190,000 m3.

Brick Gothic is a specific style of Gothic architecture common in Northeast and Central Europe especially in the regions in and around the Baltic Sea, which do not have resources of standing rock. The buildings are essentially built using bricks. Buildings classified as Brick Gothic are found in Belgium, Netherlands, Germany, Poland, Lithuania, Latvia, Estonia, Kaliningrad, Denmark, Sweden and Finland.