For those of you interested in painture and/or portraiture, El Prado museum has released a free PDF e-book titled "El retrato español en el Museo del Prado" (Spanish portraiture in El Prado museum). Inside it you can find pictures of Goya, Velázquez, El Greco, Sánchez Coello et al. commented with some history and some technical details.
The e-book is released in Spanish and French, has about 90 pages and weights about 6 mbytes. You can find them
under this link.
