The most emblematic monument of the Abruzzo region, the basilica was begun in 1287 on the orders of Pietro da Morone, who was to become Pope Celestine V in 1294. The huge façade with rectilinear coping stands out with its geometrical motifs created by the placement of white and pink stone, doorway and rose windows. On the left flank of the basilica, the Porta Santa is a fine, richly decorated Romanesque doorway. Inside is St Peter Celestine's Lombard Renaissance-style tomb.