The Romanesque cathedral was built between 1132 and 1166 by bishop Roberto of Avellino, who dedicated it to Saint Modestinus. It kept its original appearance until the end of the 17th century, when a series of refurbishments and renovations began which, continuing into the 18th century, eventually transformed the building into a Baroque one. Bishop Francesco Gallo (1855–1896) gave the cathedral a further overhaul, creating its present Neoclassical appearance. The refacing of the west front was entrusted to the architect Pasquale Cardola and was completed between 1857 and 1868, while the conversion of the interior was the work of the architect Vincenzo Varriale between 1880 and 1889. The new building was subjected to the bombing of World War II and the 1980 Irpinia earthquake, both of which made necessary further significant stabilisation and reinforcement of the structure.