The Iron Crown is one of the most important objects in the entire history of the Christian West and is venerated as a relic of the Holy Nail. Numerous coronations would have taken place with the precious tiara. Consisting of six ornate gold plates, it bears within it a circle of metal that by ancient tradition is believed to be one of the nails used in Christ's crucifixion, found by St. Helena in 326 and inserted by her into the diadem of her son, Emperor Constantine.
It is preserved in Monza Cathedral in the Chapel of Theodolinda, beautifully frescoed by the Zavattari between 1444 and 1446 with stories of the Lombard Queen, a masterpiece of late Gothic painting. The figure of Theodolinda (570-627), a Bavarian princess of the Catholic faith who married the king of the Lomgobards in 589, is rich in fascination: she is credited with founding the city and the Monza cathedral.