Riera. Countless statues, fountains and commemorative monuments have filled the park and converted it into an open-air sculpture museum. The 1930s and 1940s witnessed the creation of new gardens attributed to Chief Gardener Cecilio Rodriguez who designed and built the rose garden. Features of the Park Close to the northern entrance of the park is the Estanque del Retiro ("Retirement Pond"), a large artificial pond. Next to it is the monument to King Alfonso XII, featuring a semicircular colonnade and an equestrian statue of the monarch on the top of a tall central core. The Rosaleda (rose garden) is an early 20th century feature inspired by the Bagatelle rose garden in the Bois de Boulogne. Near the roses stands the Fountain of the Fallen Angel, erected in 1922, whose main sculpture El Angel Caído (at the top) is a work by Ricardo Bellver (1845–1924) inspired by a passage from John Milton's Paradise Lost, which represents Lucifer falling from Heaven. It is claimed that this statue is the only known public monument of Satan. The few remaining buildings of the Buen Retiro Palace, including Casón del Buen Retiro and the Salon de Reinos, now house museum collections. The Casón has a collection of 19th- and 20th-century paintings, including art by the Spanish painter Joaquín Sorolla. The Ejército, one of Spain's foremost Army museums, has moved to Toledo. Since assuming its role as a public park the late 19th century, the "Parque del Retiro" has been used as a venue for various international exhibitions. Several emblematic buildings have remained as testimony to such events, including the Mining building, popularly known as the Velázquez Palace (1884) by architect Ricardo Velázquez Bosco, who also designed the Palacio de Cristal ("Crystal Palace"), a glass pavilion inspired by The Crystal Palace in London, undoubtedly the gardens' most extraordinary building. Built along with its artificial pond in 1887 for the Philippine Islands Exhibitions, the Palacio de Cristal was first used to display flower species indigenous to the archipelago. The landscape-style gardens located in the former "Campo Grande" are also a reminder of the international exhibitions that have taken place here in the past. The Paseo de la Argentina, also popularly known as Paseo de las Estatuas ("Statue Walk"), is decorated with some of the statues of kings from the Royal Palace, sculpted between 1750 and 1753. There are now art galleries in the Crystal Palace, Palacio de