The Romanesque church of St Reparata (the substructure, built on Paleo-Christian vestiges, can be seen in the Duomo crypt) was deemed too modest for such an important city as Florence. Consequently, work on a cathedral began in 1296 to plans by Arnolfo di Cambio (the unfinished façade was replaced in 1887); the work was continued by Giotto, Pisano and Talenti and finally completed in 1436. The insoluble problem of the dome was solved with genius by Brunelleschi in 1420.