St Mary's Church, formerly the Basilica of St. Mary of the Assumption of the Blessed Virgin Mary, is a co-cathedral in the Polish city of Gdańsk. With a length of 105.5 meters it is commonly cited as largest brick church in the world. The interior vault supports 37 windows, over 300 tombstones and 31 chapels. It can hold up to 25,000 people

Construction on the church began in 1343 and was completed in 1502. Inside the high altar has a Gothic polyptych from the 1510s, with the Coronation of the Virgin depicted in its central panel. During World War II St Mary's Church suffered extensive damage resulting in forty percent of its artistic treasures being either destroyed or damaged.

Don't miss the 15th-century astronomical clock in the northern transept and the church tower. The 78-meter tower (a climb of 405 steps) houses a viewing platform with the best views of Gdańsk Old Town.