Płock (pwotsk), dramatically perched on a cliff high above the Vistula, has a long history and a pleasing old centre. It also boasts the remnants of a Gothic castle, a glorious cathedral and the finest collection of art nouveau art and architecture in the country.
Płock was a royal residence between 1079 and 1138 and the first Mazovian town to be given a municipal charter (in 1237). Its city walls were built in the 14th century and the town developed as a wealthy trading centre until the 16th century. The flooding of the Vistula in 1532, when half the castle and part of the defensive walls slid into the river, was merely a portent of further disasters to come, and the wars, fires and plagues that struck the town in the following centuries brought its importance to an end.
These days, it's first and foremost a refinery town, with a working-class, blue-collar feel, though there are enough sights to hold a visitor's interest for a day or so.