Palacio del Duque de Elduayen, Neoclassical palace in Justicia, Madrid, Spain.

The Palacio del Duque de Elduayen, also known as the Palacio del Marqués del Pazo de la Merced, stands at Paseo de Recoletos 25, on the corner of Calle de Bárbara de Braganza. It has a square plan with an interior courtyard and is freestanding on three sides: two facing streets and one facing a garden. The garden facade has a staircase with a modern temple-like entrance, once the main entrance to the palace grounds. The building has three floors plus a semi-basement, with exposed brick facades, stucco balconies, and a taller principal floor.

The palace was built between 1881 and 1882 by architect Miguel Aguado de la Sierra as a residence for José Elduayen Gorriti, who served as Finance Minister under King Amadeo I. Its construction reflects the prominence of the Elduayen family in Spanish financial circles during that period.

A commemorative plaque on the facade marks that the editorial La Lectura had its offices here and in 1914 published the first edition of Platero y yo by Juan Ramón Jiménez, who received the Nobel Prize in Literature in 1956. The building has housed the Mapfre Foundation since its restoration between 1995 and 1997.

The building stands at Paseo de Recoletos 25, at the corner of Calle de Bárbara de Braganza 16, in the Justicia area of central Madrid. It is free-standing on three sides, with two facades on the street and one facing the garden; the garden side, once the main entrance to the palace, is reached by a staircase with a modern temple structure. The interior follows the 19th-century noble layout: basement and semi-basement for pantry, storage and laundry, the main floors for the family, and attic rooms for the servants.

The palace was built on part of the plot once occupied by the Circo Price, the Madrid circus building. Its garden facade, originally the main entrance to the palace grounds, is reached by a staircase with a modern temple-like canopy added in the 1995–1997 restoration by Enrique de León García and Íñigo Ortiz Díez de Tortosa.