One of Curitiba's other widely replicated practices is its innovative creation and use of open space and brownfield (polluted former industrial site) reuse. The above image (courtesy of Ben Hejkal, www.benhejkal.com) is of UniLivre - the free university of the environment - which is an environmental education center and park in a former rock quarry. The site was reforested with native vegetation, and in the footprint of the quarry operations building a tower of treehouse-like classrooms was built, with a spiraling ramp encircling the classrooms to an amazing lookout point at the top of the quarry. The construction used old telephone poles from around the City, which the public utility was replacing with concrete, as structural elements. This iconic park is just one of many creative environmental spaces in Curitiba. Parks, including others in former quarries, floodplains, and other environmentally sensitive areas, throughout the City function as amphitheaters and play spaces while ensuring that sensitive areas are protected from development, and useful and attractive to the public.