Relics that are claimed to be the Holy Nails with which Christ was crucified are objects of veneration among some Christians, i.e., among Catholics and the Eastern Orthodox. In Christian symbolism and art they figure among the Instruments of the Passion or Arma Christi, the objects associated with Jesus' Passion. Like the other Instruments the Holy Nails have become an object of veneration among many Christians and have been pictured in paintings and supposedly recovered.
When Helena, mother of Constantine the Great discovered the True Cross in Jerusalem, the legend was told by and repeated by Sozomen and Theodoret that the Holy Nails had been recovered too. Helena left all but a few fragments of the Cross in the Basilica of the Holy Sepulchre in Jerusalem, but returned with the nails to Constantinople. As Theodoret tells it in his Ecclesiastical History, chapter xvii,
The mother of the emperor, on learning the accomplishment of her desire, gave orders that a portion of the nails should be inserted in the royal helmet, in order that the head of her son might be preserved from the darts of his enemies. The other portion of the nails she ordered to be formed into the bridle of his horse, not only to ensure the safety of the emperor, but also to fulfil an ancient prophecy; for long before Zechariah, the prophet, had predicted that 'There shall be upon the bridles of the horses Holiness unto the Lord Almighty.
One of the nails is said to have come to rest in the Iron Crown of Lombardy.
The authenticity of many of these relics is in question. The Catholic Encyclopedia remarked that given that the question has long been debated whether Christ was crucified with three or with four nails: