The Toronto ravine system is a distinctive feature of the city's geography, consisting of a network of deep ravines, which forms a large urban forest that runs through most of Toronto. The ravine system is the largest in any city in the world, with the Ravine and Natural Feature Protection Bylaw protecting approximately 110 square kilometres (42 sq mi) of public and privately-owned land. The ravine system has been presented as a central characteristic of the city, with the size of the ravine system leading Toronto to be described as "a city within a park".