It was built in the place where Severino Boezio became a martyr. San Pietro in Ciel D'Oro is an old Romanesque church erected probably between 1100 e il 1200 on a longobard preexistence.
It mantains numerous treasures: here the Sant'Agostino's corpse, one of the fathers of the church, was moved.
His corpse was stolen from the saracen pirates who brought it to Sardinia with the aim of sell it again to the Christians for its weight in gold. The Longobard King Liutprando bought it and to give hospitality to it made a church be built. The corpse of the martyr Severino Boezio rests next to the one of Agostino. Boezio is remembered by Dante in the Divina commedia with these verses "i'mi son un che, quando/ amor mi spira, noto, e a quel modo/ ch'è ditta dentro vo significando" (Pg. XXIV, 52-54).
The basilica owes his name to the fact that in ancient times the apse was covered by a first-quality gold mosaic, that was stolen by the French in1799.
Remarkable was also the politic role that the old church performed: here the german kings met each other when they were coming to Italy to establish in their diets the laws that would have regulated the kingdom.
