In the middle of the steps leading to the transept is an ancient well. The 11th century well-head is contemporary with the first church, and is a superb piece of work attributed (tentatively) to Niccolò di Angelo. It was made from the base drum of an ancient column, and shows four figures in relief standing under a richly decorated colonnaded arcade. The figures are: Christ holding an open book; a bishop (either St Paulinus or St Adalbert); Emperor Otto III, with a very Germanic mustache and holding a disc with an image of the church, and St Bartholomew holding a book and the knife used to flay him.