Stained-glass window V20 of Milan Duomo depicts the Stories from Saint John's Book of Revelation. Like the other two impressive apse windows, it was amongst the first works carried out for the Duomo: already at the beginning of the 15th century the Fabbrica was already working to appoint the best glassmakers of the time. It is also known as the window "della raza" for the imposing, flaming sun at the top, a representation of Christ (Sol Iustitiae), and heraldic symbol of the Visconti family, under whose aegis the construction of the Cathedral began. The only surviving panels from the first phase of construction are found in the upper part of the window; the original lower register was completely replaced in the mid-19th century with panels from the Bertini workshop.