Its 12th century cathedral contains the tombs of Ladislaus Herman (died 1102) and Boleslaus III the Wrymouth (died 1138) - the dukes of Poland. Some historians say that Plock was the capital city of Poland during their reign (1080-1138).
The main industry is oil refining - the country's largest oil refinery is located there (it is served by a large pipeline leading from Russia to Germany.
This city is the main seat of the Mariavite bishops. Their most important church was built here in the beginning of 20th century - it is called Temple of Mercy and Charity.