On the south side of the cathedral, this site was the headquarters of the biggest diocese in England during the Middle Ages. Launched in 1150, it held great power until it was sacked during the civil war in the 1640s. Allowed to ruin over the centuries, it has been opened to the public, who can explore its ruins, including an intact entrance tower, a public hall, and a vaulted undercroft. You can also wander its grounds, taking in panoramic views of the city.