Titulus Crucis (Latin for "Title of the Cross") is a piece of wood, claimed to be a relic of the True Cross, kept in the church of Santa Croce in Gerusalemme in Rome. Christian tradition claims that the relic is half of the cross's titulus (inscription) and a portion of the True Cross. It is generally either ignored by scholars or considered to be a medieval forgery.
The board is made of walnut wood, 25x14 cm in size, 2.6 cm thick and has a weight of 687 g. It is inscribed on one side with three lines, of which the first one is mostly destroyed. The second line is written in Greek letters and reversed script, the third in Latin letters, also with reversed script.
The Church of Santa Croce in Gerusalemme was built about 325 AD by Saint Helena (the mother of Emperor Constantine the Great) after her pilgrimage to the Holy Land, during which she reportedly located the True Cross and many other relics which she gave to the new church. The Titulus Crucis is alleged to have been among these relics. Sometime before 1145 the relic was placed in a box which has the seal of a cardinal who became Pope in 1144  and apparently forgotten until February 1, 1492, when it was discovered by workmen restoring a mosaic, hidden behind a brick with the inscription Titulus Crucis.
In 2002, the University of Arizona conducted radiocarbon dating tests on the artifact, and it was shown to have been made between 980 and 1146 AD. The carbon dating results were published in the peer-reviewed journal Radiocarbon. The Titulus Crucis recovered from the residence of Helena is therefore most likely a medieval artifact; some have proposed that it is a copy of the now-lost original.
At the time of Egeria's pilgrimage to Jerusalem in 383 a "title" was shown as one of the relics at Jerusalem : "A silver-gilt casket is brought in which is the holy wood of the Cross. The casket is opened and (the wood) is taken out, and both the wood of the Cross and the title are placed upon the table." The 6th century pilgrim Antoninus from Piacenza describes a Titulus in Jerusalem and its inscription: it said «Hic est rex Iudeaorum» (Here is the king of the Jews), while the one kept in Rome shows «Iesus Nazarenvs Rex Iudeaorum» (Jesus the Nazarene king of the Jews).
Carsten Peter Thiede suggested that the Titulus Crucis is likely to be a genuine part of the Cross, written by a Jewish scribe. He cites that the order of the languages match what is historically plausible rather than the order shown in the canonical New Testament because had it been a counterfeit, the forgerer would surely have remained faithful to the biblical text. Joe Nickell refers to this argument as "trying to psychoanalyze the dead." saying that "Forgers — particularly of another era — may do something cleverer or dumber or simply different from what we would expect."
- Morris, Colin The sepulchre of Christ and the medieval West: from the beginning to 1600 OUP Oxford (17 Mar 2005) ISBN 978-0-19-826928-1 p.32 
- Byrne, Ryan; McNary-Zak, Bernadette Resurrecting the Brother of Jesus: The James Ossuary Controversy and the Quest for Religious Relics The University of North Carolina Press (15 Aug 2009) ISBN 978-0-8078-3298-1 p.87 
- 'TITULUS CRUCIS'..Evidence that the Actual Sign Posted Above The Lord on The Cross Has Been Located?
- Nickell, Joe Relics of the Christ The University Press of Kentucky (1 Mar 2007) ISBN 978-0-8131-2425-4 pp87-88 
- Francesco Bella; Carlo Azzi (2002). "14C Dating of the Titulus Crucis". Radiocarbon (University of Arizona) 44 (3): 685–689. ISSN 0033-8222.
- Latin original: ... et affertur loculus argenteus deauratus, in quo est lignum sanctum crucis, aperitur et profertur, ponitur in mensa tam lignum crucis quam titulus. (Itinerarium Egeriae 37,1)
- The Antoninii Placentini Itinerarium can be read in Corpus Christianorum, Series Latina, vol. 175, 130