An early version of the castle was built on the site in the 16th Century. After it was destroyed in a fire, a new residence was commissioned by king Philip V. A Berniniesque design was prepared by Giovanni Battista Sacchetti, Ventura Rodríguez, Francesco Sabatini, and Filippo Juvarra. The new castle was ready in 1764, in time for Carlos III to inaugurate his reign in it. Over time, its interior was decorated with works by such artists as Velázquez, Tiepolo, Gasparini, Mengs, Caravaggio, Juan de Flandes, and Goya. The castle rooms holds several rare collections of great historical significance. The Royal Armoury features 13th-Century weapons. Other chambers hold the only complete Stradivarius string quintet in the world and precious collections of art, porcelain, tapestry, and furniture.