The crucifixion of Christ took place at Calvary, which is also called Golgotha, the Hebrew word for 'the place of a skull', [Mark:15:22].
According to an ancient Eastern tradition, Adam was buried on Golgotha and his son, Seth, planted a tree on his grave which was later used to make Christ's cross. From the late 10th century onwards in western art Adam's skull was sometimes shown at the foot of Christ's cross as a reminder of this story.
