Płock

Plock, officially the Ducal Capital City of Plock, is a city on the Vistula river in the Masovian Voivodeship of central Poland, with 116,962 inhabitants recorded on 31 December 2021. From 1079 to 1138 it was the capital of Poland, and its Cathedral Hill, along with Plock Castle and the Catholic cathedral containing the sarcophagi of several Polish monarchs, is listed as a Historic Monument of Poland; the city served as the main administrative center of Mazovia in the Middle Ages before the rise of Warsaw and later remained a royal city of Poland. Plock is the seat of the Roman Catholic Diocese of Plock, founded in the 11th century, and is the global headquarters of the Mariavite Church; it is also home to Poland's oldest school and its largest oil refinery.