city, Mazowieckie województwo (province), central Poland, on the Vistula River.

First chronicled in the 10th century, Płock is the oldest community in Mazowsze (Mazovia), having served as the seat of Polish rulers from 1079 to 1138. It received town privileges in 1237 and prospered as a trading centre through the 17th century. In 1793 Płock passed to Prussia; it was returned to Poland in 1918. The town was badly damaged during World War II, at which time it was known as Schröttersburg.

The economy of Płock is based on oil refining and modern petrochemical and plastics works. There is also production of agricultural machinery and foodstuffs. Płock is located on a rail line and has riverboat service and good road links with the rest of Poland. The Museum of Mazovia specializes in the artwork and furnishings of the Art Nouveau period. Pop. (2002) 128,366.