Philip IV of Spain (r. 1621–65) was known as the Planet King, and he shone more brightly in the sphere of the arts than would the Sun King, Louis XIV. The focus of much of his patronage was the Buen Retiro Palace in Madrid. Now largely destroyed, it was once hung with some 800 paintings, specially gathered for it during the 1630s. They included work commissioned from the finest masters in Europe, including Velázquez, Zurbarán, Ribera, Rubens, Claude, Poussin, Jan Both, Herman van Swanevelt, Domenichino, and Lanfranco. This book provides a comprehensive guide and illustration of the paintings that were once brought together for the Buen Retiro Palace. All paintings recognized (many for the first time) to have belonged to this extraordinary enterprise are illustrated.