The lower section of Sienna Cathedral Façade was the work of Giovanni Pisano. It is distinguished by three large, elaborate, polychrome arches that herald the monumental doors.
The upper section is rich in ornamental elements. Small towers enclose the façade, cusps and pinnacles define it and a highly decorated cornice frames the plain rose window.
It is true that the whole is not completely homogeneous but at first sight, and this is the genius of the work, the assymmetry between the original lower section and the later upper extension is not apparent.
The mosaics are 19th century replications of earlier pieces.