Madrid Río Park: Puerta del Rey

Madrid Río Park was the result of a project completed in 2011 to take the M-30 main road underground running parallel to the Manzanares River. It is universally accessible, a place for leisure and cultural activities with cycle paths, sports tracks, children's playgrounds and fitness routes, among other amenities. It also boasts a number of brand new bridges whose unusual design has turned them into new urban icons. 

+ info: https://www.esmadrid.com/en/tourist-information/madrid-rio-park