In the past it was believed that the town of Muggia Vecchia had ceased to be inhabited after its destruction by the Genoese of Pagano Doria in 1353.

Indeed, it was destroyed, leaving the basilica standing, by the Triestines, in constant struggle against the people of Muggia due to the salt pans.

Before the destruction of the town, the parish of Muggia Vecchia was very important and was officiated by a chapter of canons.

[2] The basilica, which measures 12.25 × 18.30 metres, has a "facciata a salienti" with a small bell gable.

From the original structure remain the ambon, the lectern and two large and wide marble transennas or pluteus-shaped marble balustrades of Lombard art, datable to the Lombard period of King Liutprand (8th century) or in any case to the period of the Liutprandean Renaissance, 8th-9th century.