The Spanish National Observatory (Spanish: Observatorio Astronómico Nacional de España, OAN) is an astronomical observatory with several facilities in the Madrid area.

The Observatory has published a yearbook (the Anuario del Observatorio Astronómico de Madrid) since the 19th century.

Equipped with a Herschel telescope, it took over the purely astronomical work of the naval observatory, the Real Instituto y Observatorio de la Armada, in the south of the country.

The building was designed by Juan de Villanueva and represents one of the highlights of Spanish neoclassical architecture.

The Observatory houses historic scientific equipment and can be visited by prior arrangement.