The tradition that had Emperor Constantine building a basilica in 324 AD on top of the vineyard that was supposed to be the site of Saint Paul's execution and burial, was confirmed by the Pope, according to an article in the Guardian today.
Apparently, a tomb was discovered outside the walls of Rome in 2006. An independent lab carbon dated the bone fragments to between the first and second centuries. A purple cloth, incense, and other items were found in the tomb, but no marker that says absolutley who we have here. No archeologist would verify that without more evidence, but it is an interesting slice of history here, if true.
To read the whole article, go here.