Ringing the city is the Anillo Verde (Green Belt), a series of interconnecting parks, ponds and marshes linked to one another by 31km of cycling paths, which was established in 1994. Altogether, some 206 hectares of woodland, lakes and grassy expanse have been restored. It's an important ecological zone that attracts numerous waterfowl, as well as providing a refuge for the rare European mink and very tame herds of deer. Bird hides (blinds) are scattered around the lake shores.