The present chapel was commissioned by Pope John IV (640-642) in honor of St Venantius of Salona and other Dalmatian martyrs. Pope John was a Dalmatian himself, and seeing that the Slavs where overrunning his country he brought the relics of the more important Dalmatian saints here and enshrined them. The project was completed under Pope Theodore I (642-9), and involved an impressive sanctuary mosaic. In 1674, the Ceva family commissioned Carlo Rainaldi to restore the chapel. A restoration in 1967 left the interior mostly in bare brick.