The Archaeology of Roman Crucifixion
Source of photos: http://www.joezias.com/CrucifixionAntiquity.html
First is a photo of the archaeological evidence for crucifixion, found in a first century AD tomb at Givat ha-Mivtar, to the north of Jerusalem in 1968. The man died in his twenties, and according to the inscription on the Ossuary in which he was placed was 'Jehohanan the son of HGQWL'. The remains of his heel to the right of the photo clearly show the nail that pierced it (a reconstruction to the left makes it clearer). Olive wood fragments were found between the large nail head and the bone, which show that a wooden plaque of wood was added to make it harder for him to pull his leg free from the cross.
There have been long theological debates over the centuries about how Christ was crucified: with a nail through both feet, or a nail through each foot. Jehohanan's nail is too short to have gone through both ankles.
Joe Zias and a colleague re-examined the evidence, and published the reconstruction of how the man had been crucified, as seen in the drawing above: J. Zias and E. Sekeles, The Crucified Man from Giv'at ha-Mivtar: A Reappraisal, Israel Exploration Journal 35, 1985: pp. 22-27.
It's the best account I know of the archaeological evidence for crucifixion.