A microscopic examination of the fragments of the Cross scattered through the world in the form of relics reveals the fact that it was made from a pine-tree (Rohault de Fleury, "Mémoire sur les instruments de la Passion", Paris, 1870, 63).
According to an ancient, but somewhat dubious, tradition the Cross of Jesus Christ measured in length very nearly 189 inches (4.80 metres), from 90½ to 102½ inches (2.30 to 2.60 meters).
As noted by the Evangelists, two thieves were crucified, one on either side of Christ.
Their crosses must have resembled the one on which He suffered; in Christian art and tradition they generally appear lower (St. John Chrysostom, Hom. i, xxvi, on I Cor.; on Rom., v, 5).
Finally, a large portion of the cross of the good thief (traditionally known as Dismas) is preserved at Rome in the altar of the Chapel of the Relics at Santa Croce in Gerusalemme.
God bless'