Located behind the Prado Museum, Retiro Park is one of the largest and most popular parks in Madrid. The park was originally the private grounds of the Spanish royal family and didn't open to the public until 1868.
Highlights include the Palacio de Cristal, a stunning glass-and-iron pavilion built in 1887 to exhibit plants from the Philippines, and the Estanque Grande, a large artificial lake where you can rent rowboats by the hour. The Rosaleda rose garden is at its best in May and June.
The park also hosts rotating art exhibitions in the Palacio de Velazquez and the Crystal Palace, both managed by the Reina Sofia museum. On weekends, street performers, puppet shows, and fortune tellers set up near the lake.