The Marriage of the Virgin is one of Murillo's finest paintings. The Virgin takes the hand of Joseph as their marriage is blessed by the high priest of the temple of Jerusalem, Zacharias. The Holy Spirit descends on the couple, and Joseph's rod symbolically bursts into flower. A small, delicate work on a mahogany panel, it would have been intended for a private collection. Talks: Lucy Davis,1 and 11 March at 1pm Free, no need to book. Talks in the galleries are strictly limited to 25 people with places allocated on a first come first served basis.