The Diadem unambiguously identifies the head as that of a late Roman emperor, and on stylistic grounds it has been dated between the 4th and 6th centuries, with several scholars identifying it as a depiction of Justinian. The flattened nose is ostensibly the result of damage and subsequent repolishing.[1] It is "one of the most significant" of the ornamental trophies that adorn the Basilica's facade,[2] looking straight into the direction of Constantinople.
A headless porphyry statue kept at the Archiepiscopal Museum in Ravenna has been hypothesized to belong to the same original.[3]
The condottiereFrancesco Bussone da Carmagnola was beheaded on 5 May 1432 on the Piazzetta, where his head was presumably left exposed for some time, leading to the sculpture's traditional nickname.[1]
Side facade of St Mark's Basilica, with Carmagnola at the far left of the upper-level railing