Żabie Doły (roughly translated as "Frog Ditches") is a nature and landscape protected area in Silesia, located entirely within the limits of the cities of Bytom, Chorzów and Piekary Ślaskie. The local landscape resembles that of Masuria, a lake district in north-eastern Poland. Żabie Doły is a protected area of endangered species, including little bittern, Eurasian bittern and mute swan. Interestingly, it owes its appearance to many centuries of human activity, in particular underground mining and metal smelting.