The cathedral was built on the site of the former pieve of San Basilio .
Was under construction from 1204 to 1474 , when the upper part of the west front was completed by Leonardo Riccomanni of Pietrasanta .
The cathedral was built on the site of the former pieve of San Basilio and was under construction from 1204 to 1474 , when the upper part of the west front was completed by Leonardo Riccomanni of Pietrasanta .