In 1902, a national contest was held to design a monument for King Alfonso XII at the initiative of the Queen Mother Maria Christina of Austria.

The winner was the architect José Grases Riera, whose design consisted of a grand colonnade alongside a pond in El Retiro, with several sculptures surrounding an equestrian statue of the king, with everything constructed in bronze and marble.

[1] It was the first of many commemorative statues (by artists such as Mariano Benlliure, Josep Clarà, and Mateo Inurria) that were added to parks in Spain over the last century.

There are also two lions in each of the lateral access paths to the semicircle; these were carved by Francisco Javier Escudero Lozano, Antonio Bofill, Eusebi Arnau, and Campmany.

At each side of the central access way to the colonnade are "El Ejército" ("The Army") by José Montserrat and "La Marina" ("The Navy") by Mateo Inurrria.