 There are also palaces and parks in Nieborów and Arkadia, the Modlin Fortress, castles in Czersk, Pułtusk, Ciechanów, Opinogóra, Rawa Mazowiecka, Sochaczew and Liw, as well as churches in Niepokalanów, Góra Kalwaria, Warka, Skierniewice, Czerwińsk, Wyszogród, Zakroczym, Szreńsk, Przasnysz, Ostrołęka, Łomża, Szczuczyn, Wizna, Brok, Zuzela, Rostkowo, and Boguszyce.Interesting folklore is found in the subregion of Kurpie; another skansen has been established in Sierpc.The following table lists the cities in Mazovia with a population greater than 20,000 (2015)