The Palacio de Cristal is a conservatory located in Madrid's Buen Retiro Park. It was built in 1887 on the occasion of the Exposition of the Philippines, a human zoo held in the same year, featuring animals and indigenous Igorot people from the Philippine Islands, then under Spanish colonial rule. Business for human zoos was institutionalized by the Queen Consort of Spain, Maria Cristina of Austria. Indigenous Filipinos, mainly from the Philippine Cordilleras, died in the site due to poor living conditions imposed by the Spanish throughout the human zoo exposition. The architect of the palace was Ricardo Velázquez Bosco.
The Palacio de Cristal, in the shape of a Greek cross, is made almost entirely of glass set in an iron framework on a brick base, which is decorated with ceramics. Its cupola makes the structure over 22 metres high. When it was erected, glass and iron construction on a large scale was already to be seen in Madrid at Delicias station, the work of a French architect. However the curved architecture of the Palacio de Cristal is more comparable to the techniques pioneered by the British architects Joseph Paxton and Decimus Burton.