The portal, profusedly decorated by floral and animal depictions, was initially erected in the cathedral during the reign of Ruggero I of Sicily (1031-1101).
On the uppermost floor of the facade, housing the church bells, rises a broken pediment, decorated with a relief depicting Saint Agatha, flanked by two reclining angels offering her the palm of martyrdom.
Remains of the 15th-century city walls form part of the north side of the church and the base of its facade.
The interior of the church contains a silver chest with her relics, and lava slabs putatively with imprints of her small feet.
The painting depicts the Ancient Roman amphitheater in Catania behind the saint, part of which has been uncovered in Piazza Stesicoro in front of the facade of the adjacent Sant'Agata alla Fornace.