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 from 1841 to 2010 when the military collections were put on display at the Alcázar of Toledo.
Wikipedia https://en.wikipedia.org/wiki/Hall_of_Realms
Coordinates 40°24'56.814" N -3°41'25.219" E