The crypt of Sant’Eusebio, now isolated in Piazza Leonardo da Vinci, is all that remains of a church probably founded by the Longobards. It is, in fact, recognized as the Aryan cathedral of the city, remembered by Paolo Diacono in the years of King Rotari (636-652) and rededicated to Saint Eusebius, a fierce enemy of the Arian heresy, after the conversion of the Lombard population to Catholic orthodoxy , in the second half of the seventh century. The church building was rebuilt in proto-Romanesque form in the 11th century, remodeled variously between the 16th and 17th centuries, rebuilt again in the 18th century and razed to the ground in 1923 to make room for the Palazzo della Posta.