Apr - Sept: 6 a.m. - midnight
Oct - Mar: 6 a.m. - 10 p.m.
Admission free.
Wikipedia https://en.wikipedia.org/wiki/Parque_del_Buen_Retiro,_Madrid
Official Tourism Website Madrid http://www.esmadrid.com/en/tourist-information/parque-del-retiro/
Address 1 Paseo del Duque Fernán Núñez, Madrid 28009, Spain
Coordinates 40°24'37.646" N -3°41'13.458" E