It is difficult to report on the history of Spanish art for two reasons. First, you don't see a lot of Spanish art in museums in other countries. A very large portion of Spain's most important artwork has been retained in Spain, mostly at the Prado and the Reina Sofia Museums. The second problem is that the Prado doesn't allow photography at all, and the Reina Sofia prohibits photography of its most important exhibits.
The one place you can photograph examples of Spain's rich art history is an academy founded by royal decree in the 1700s, the Royal Academy of Fine Arts. Here you can see works by El Greco and Murillo, and many minor works by Francisco Goya.
The first Spanish artist of the modern era was Joaquín Sorolla, whose work derives from Impressionism. An extensive selection of his work may be enjoyed at the Sorolla Museum, located in the artist's studio-mansion.
Several Spanish artists became well-known in the 20th century, including Pablo Picasso and Salvador Dalí. Modern Spanish art is exhibited at the Reina Sofia Museum.
During our visit, the Reina Sofia was also offering two special exhibits from Bern, Switzerland, that presented a fairly comprehensive review of art of the early 20th century.
Museums to Visit
History of Spanish Art: Royal Academy of Fine Arts
Joaquín Sorolla: Sorolla Museum
20th Century Spanish art and Special Exhibits: Reina Sophia Museum
Royal Academy of Fine Arts
Sorolla Museum (same article as above, half-way down)
Reina Sophia Museum
Stars of Spanish Art
El Greco, Velázquez, Murillo, Goya, Sorolla, Picasso, Miró, Dalí
International Art Stars
Van Gogh, Gauguin, Ferdinand Hodler, Ernst Kirchner, Edvard Munch, Alexej von Jawlensky, Georges Braque, Picasso, Fernand Léger, Paul Klee, Piet Mondrian, Andy Warhol, Gerhard Richter