Plock, city in central Poland, capital of Plock Province, about 100 km (about 60 mi) northwest of Warsaw. Located on the Wisla River, Plock is a river port, road junction, and industrial center. Its petrochemical refinery is the endpoint for the Friendship Pipeline, an oil pipeline that originates in Russia. Industries in Plock manufacture foodstuffs, river vessels, building materials, clothing, and metal and wood products. Plock's historic monuments are well preserved and include a 12th-century Roman Catholic cathedral containing the tombs of Polish kings. The city also has Roman Catholic churches built between the 14th and 17th centuries by Dominicans, Benedictines, and Jesuits. Other historic attractions include 14th-century fortifications and a 19th-century bishop's palace. The city has two museums, an old prints library, and a zoo. Plock was founded in the 10th century. It became a Roman Catholic bishopric in 1075. From 1079 to 1138 Plock was the seat of Polish kings. From the 11th century it was the capital of the Polish duchy of Mazovia. In 1793 it came under the control of Prussia, a kingdom of Germany. Plock came under the rule of the Russian Empire in 1815 but in 1918 became part of an independent Poland. During World War II (1939-1945) Plock was occupied by German forces. Population (1997 estimate) 127,700.