Below is a video from a few years ago called "the Gospel of Caesar." Herein Francesco Carotta shows how the wax image of Julius Caesar was displayed on a cross, or tropaeum, at his funeral, March 17th or 20th, 44 BCE. He also lays out his hypotheses on how Christianity may be derived from the first Roman Imperial Cult of Divus Julius, and how the Gospel of Mark may be derived from a now-lost biography of Julius Caesar. Given the immense wealth of data he as dug up backing his hypotheses, I find the verity of them to be quite likely.
More details to be found in the book: "Jesus was Caesar" by Francesco Carotta ( http://books.google.it/books/about/Je..., http://www.scribd.com/doc/4090002/Jes... ), and at the blog, Divvs Ivlivs.