Pelplin is a town in northern Poland, in the Tczew County, Pomeranian Voivodship. Population: 8,320. Pelplin is located in the ethnocultural region of Kociewie in Pomerania. It is home to one of the finest collections of medieval art in Poland held at the Diocesan Museum in Pelplin. It is known for the landmark Gothic Pelplin Cathedral, former abbey church, one of the largest Gothic churches in Poland. The former Pelplin Abbey is the seat of the Roman Catholic Diocese of Pelplin.