Co-Cathedral Basilica of the Most Holy Trinity, Chełmża

The Cathedral of Culmsee — formally the Co-Cathedral Basilica of the Most Holy Trinity — is a Gothic brick church in the small city of Chełmża in the Kuyavian-Pomeranian Voivodeship of north-central Poland. Built in the 14th century, it served as the seat of the historic Diocese of Chełmno (Kulm), founded in 1243 under the Teutonic Knights as part of their mission to Christianize the Baltic frontier. Today it functions as a co-cathedral of the Diocese of Toruń and holds the rank of Basilica minor. The structure displays hallmarks of the North Polish brick-Gothic tradition: pronounced exterior buttresses, slender tracery windows, and a soaring nave vault. Listed as an immovable monument of Poland, it is one of the most significant medieval ecclesiastical buildings in the region.