Dan Cruickshank explores the mysteries and secrets of the bridges that have made London what it is. He uncovers stories of bronze-age relics emerging from the Vauxhall shore, of why London Bridge was falling down, of midnight corpses splashing beneath Waterloo Bridge, and above all, of the sublime ambition of London's bridge builders themselves.

What really went on at the ancient Greek oracle at Delphi, how did it get its awesome reputation and why is it still influential today? Michael Scott of Cambridge University uncovers the secrets of the most famous oracle in the ancient world. A vital force in ancient history for a thousand years it is now one of Greece's most beautiful tourist sites, but in its time it has been a gateway into the supernatural, a cockpit of political conflict, and a beacon for internationalism. And at its heart was the famous inscription which still inspires visitors today - 'Know Thyself'.