Madrid’s answer to New York’s Central Park is a warren of paths carved in green with a large, central man-made lake and plenty of space (330 acres) for lolling about. Originally conceived as a royal garden, Retiro has been a public park for 300 years. Madrileño families arrive in droves on Sundays, many with picnics or on bicycles, to relax and breathe a bit or play soccer. In the late 1880s the Palacio de Cristal, a palace-like pavilion entirely of glass, was built in the center. Modeled after London’s Crystal Palace greenhouse, it now hosts occasional exhibits.