Madrid is the capital and largest city of Spain. It is the third-most populous municipality in the European Union after London and Berlin, and the fourth-most populous urban area in the European Union after Paris, London, and the Ruhr Area. Due to its economic output, standard of living, and market size, Madrid is considered the major financial center of the Iberian Peninsula; it hosts the head offices of the vast majority of the major Spanish companies, as well as the headquarters of three of the world's 100 largest companies (Telefónica, Repsol-YPF, Endesa). While Madrid possesses a modern infrastructure, it has preserved the look and feel of many of its historic neighborhoods and streets. Its landmarks include the huge Royal Palace of Madrid; the Teatro Real (Royal theatre) with its restored 1850 Opera House; the Buen Retiro park, founded in 1631; the imposing 19th-century National Library building (founded in 1712) containing some of Spain's historical archives; an archaeological museum of international reputation; and three superb art museums: Prado Museum, which hosts one of the finest art collections in the world, the Museo Nacional Centro de Arte Reina Sofía, a museum of modern art, and the Thyssen-Bornemisza Museum, housed in the renovated Villahermosa Palace. The population of the city is roughly 3.2 million (December 2005), while the estimated urban area population is 5.1 mio.