Andrew Graham-Dixon travels to Northern Spain to visit some of the world's oldest works of art, hundreds of meters beneath the surface of the earth. In limestone caves he is astonished to find a series of vivid paintings, some of which are over 33,000 years old, which appear to link modern man to our ice age ancestors. Back in London, the British Museum is staging one of its most ambitious exhibitions yet, Ice Age Art: Arrival of the Modern Mind. Andrew gets a behind-the-scenes preview of the extraordinary highlights and discovers that the world's first commissioned artists were producing highly sophisticated work tens of thousands of years before he previously imagined. The programme includes contributions from the British Museum's director, Neil MacGregor, and artist Antony Gormley.