Best museum you've never heard of - 2006
Hispanic Society of America
Tucked away behind a courtyard off 155th and Broadway, the Hispanic Society of America houses the biggest collection of Spanish art outside Spain. It's free—funded in perpetuity by the eccentric railroad heir Archer Milton Huntington, who packed the 1908 beaux arts building with the spoils of a 50-year shopping spree, items spanning the Bronze Age to the 20th century. El Greco's Pietá is here, and so are golden-age masterworks by Velázquez, Zurbarán, and Ribera. A priceless Goya commands center stage: his portrait of the Duchess of Alba, with whom he was rumored to have had an illicit affair. Even more impressive is the rare books library, which holds 15,000 volumes from before 1701, including first editions of Don Quixote and La Celestina, plus royal patents, maritime charts, illuminated Bibles, and the most dazzling Korans since the fall of Granada. El Prado's facade should turn green with envy.