It is well–known from literature that the Romans crucified rebels and criminals. In 1968, an ossuary (bone box; see below) was found, among others, in a tomb in north Jerusalem in which were the bones of a 28 year old man and those of a child.
A 4.3 inch nail penetrated the right heel bone of the man. A piece of wood was placed on each side of the heel prior to the pounding of the nail to affix the person to a cross.
Clearly visible is the Hebrew writing of the name “Yehohanan son of Hagkol.” Note the two clear lines. Above and to the right of the name “Yehohanan,” in the first line, is another faint inscription (click on image to enlarge to view inscription).
The above picture represents a scholarly reconstruction of how Yehohanan son of Hagkal was crucified. Note how his arms are tied to the cross—no nails were found in his hands or wrists. In contrast, Jesus of Nazareth’s hands were nailed to the cross—Thomas wanted to see the “mark of the nails in his hands” (John 20:25).
Revision — In a PBS program on Jesus, (aired 4 April 2017) the heel bone with nail were taken out of a small storage box located in a huge warehouse. Thus, it does not appear that the original comment (deleted) regarding its “location” was correct.
For a convenient description of this find see pp 318–22 in Clyde E. Fant and Mitchell G. Reddish, Lost Treasures of the Bible — Understanding the Bible Through Archaeological Artifacts in World Museums. Grand Rapids, MI: Eerdmans, 2008.