Guillaume Dufay (1400 - 1474) was a French composer heralded as the leading composer of the 15th century. His works include Masses, songs, isorhythmic motets and hymn settings. Not known as an innovator, Dufay's compositional strength lies in its overwhelming control, grace and beauty.

These striking qualities are apparent in his famous isorhythmic motet Nuper rosarum flores. Like most of Dufay's motets, this work is an occasional piece written for a specific event, namely the consecration of the church of Santa Maria del Fiore at Florence in 1436. Dufay followed closely the designs of architect Filippo Brunelleschi in his compositional structure for this piece. The music's overall rhythmic proportions correspond exactly with the proportions of the cupola of the cathedral to which the work is dedicated. The motet uses the theme "Terribilis est locus iste" as its cantus firmus.