National Gallery, London has an extensive Velaquez exhibit planned for the autumn of this year. He produced many magnificent paintings of the Spanish royal family - sort of the Spanish Holbein but a much better (yes!) artist. (I like Holbein he's fantastic - Velaquez is better) He's credited with creating 'the' best masterpiece ever (disputed of course) 'Les Meninas' which will not be leaving the Prado for this exhibit.
More info in the article on the NG - right at the end including dates and some images - Philip IV.