Opposite the western entrance of the mosque, the Madrassa Halawiyya was built in 1245 as a theological college on the site of what was the 6th-century Cathedral of St Helen. The prayer hall incorporates all that remains of the cathedral, a semicircular row of six columns with intricately decorated, acanthus-leaved capitals. The cathedral was seized by the Muslims in 1124 in response to atrocities committed by the Crusaders. The madrassa was undergoing restoration work at the time of writing, but remained open.
