Complex sentence: It was completed during the 1250s, but almost completely rebuilt on Baroque designs of Bartolomeo Pettirossi, about 1627, with a façade-by Matteo Nigetti (1637) It was restored in 1872.
Split into simpler sentences: It was completed originally during the 1250s, but almost completely rebuilt around 1627 in Baroque-style by the architect Bartolomeo Pettirossi. Soon after, a new façade (1637) was erected using designs by Matteo Nigetti, It was restored in 1872.