This earth mound with an 80m diameter was raised between 1820 and 1823 in honour of Tadeusz Kościuszko (1746-1817), leader of the 1794 national insurrection. Reaching a height of 34m, it stands atop a hill (333m) known as Sikornik. In 1853, a brick military citadel was built around it, occupied by a hotel and the premises of the private RMF radio station. Get to the top of the mound (admission fee) via the little neo-Gothic St Bronisława Chapel to the rear.