The chapel was converted from the former sacristy by order of Pope Julius III, and was originally dedicated to St Paulinus of Nola. After the restoration of 1583 the relics of SS Adalbert and Paulinus were enshrined here, and the chapel was given to the millers in 1604. They left in 1846, and St Paulinus was taken to Nola in 1909. So, the chapel is now usually described as dedicated to St Adalbert. The frescoed altarpiece, of 1665, shows The Assumption of Our Lady, with SS Paulinus, Adalbert, Exuperantius and Marcellus.

(Another photo of the altarpiece here)