Iron Crown of Lombardy, originally an armlet or perhaps a votive crown, as suggested by its small size, that was presented to the Cathedral of Monza, where it is preserved as a holy relic. No firm record exists of its use for coronations before that of Henry VII as Holy Roman emperor in 1312.
The Iron Crown of Lombardy is composed of a broad circle of six plates of gold joined to each other by hinges and kept rigid by an interior ring of iron not quite 0.5 inch (1.25 cm) broad. It is decorated with jewels and translucent enamel and is apparently of Byzantine workmanship. The iron ring does not appear in early descriptions, and possibly it was added in the 12th century; only about 1585 or later was it described as being made from a nail used at the Crucifixion of Christ. After much argument the Congregation of Relics at Rome in 1717, though giving no definite ruling on the point, authorized the exposure of the crown for veneration.