Hall of Realms

The Salón de Reinos or salón grande is a 17th-century building in Madrid, originally a wing of the Buen Retiro Palace. The Salón de Reinos and the Casón del Buen Retiro are the only survivors of the original grand scheme of the palace.
Built between 1630 and 1635, the Hall of Realms housed the largest paintings in the royal collection, now all in the Museo del Prado. It is named after its paintings of the coats of arms of the 24 kingdoms which formed the Kingdom of Spain at the time of Philip IV of Spain.

The building served as the Museo del Ejército until 2010 when the military collections were put on display at the Alcázar of Toledo.
The Prado Museum acquired the vacant building to display part of its collections and made its renovation the subject of an architectural competition. The brief was to redesign the space as part of the campus of the art museum for its 200th anniversary. It was won in 2016 by a scheme from the British firm Foster and Partners and the Spanish firm Rubio Arquitectura.

Wikipedia