The architecture of Madrid has preserved the look and feel of many of its historic neighbourhoods and streets, even though Madrid possesses a modern infrastructure. Its landmarks include the Royal Palace of Madrid, the Royal Theatre with its restored 1850 Opera House, the Buen Retiro Park (founded in 1631), the 19th-century National Library building (founded in 1712) containing some of Spain's historical archives, a large number of national museums, and the Golden Triangle of Art located along the Paseo del Prado and comprising three art museums: Prado Museum, the Reina Sofía Museum, and the Thyssen-Bornemisza Museum, which completes the shortcomings of the other two museums. Cibeles Palace and Fountain have become the monument symbol of the city.