I believe in the revisionist approach to Pre-Columbian US history, but Burrows Cave is a scam, riddled with a rogue's gallery of suspicious actors. The Mormons are big supporters of Burrows Cave - they use it to help support their religion. Don't give them any money for the artifacts - they're recently made.
I hate to be a wet blanket on pre-Columbian contact between the Old world and the New (in fact I am firmly convinced it took place on a limited scale and have been working on a book on this subject) unfortunately the Burrows Cave 'artifacts' can be traced to a late 19th century religious cult, not across the ocean to ancient visitors. The leap to include the lost treasure of King Juba is quite a leap in my opinion, however the possibility of the African king's treasury having been shipped away to the Americas does remain - it is a fact that the Romans never did locate it despite having sent troops chasing it across the Sahara. The treasury probably included several thousand talents of silver and possibly over a thousand talents of gold - quite a fortune by today's standards.
For those interested in finds of ancient Old World origins discovered in America, here is one site with a few items:
Note that the so-called Bar Kochba ancient Hebrew coins found in Kentucky were discovered to be modern fakes, however this is not the case with the Roman, Punic, Greek and Numidian coins.