Ya ought to read Rick Osmon, he's done research on the Ohio Valley concerning possible Roman forts and infrastructure. Interesting stuff.
There have been Roman coin finds in the Americas, and contrary what some dumbasses seem to think, collectors of ancient coins don’t go out hiking with their collections, or spelunking with them, for that matter. There have been at least two finds of Roman coins (total not even a handful) somewhat near this Devil’s Backbone site.
That said, it doesn’t really take a continuity of technology to figure out how to pile up Earth, and there are obvious reasons to live on an elevated area when you live by the river — and the portraiture from the mounds (there were three separate cultures in succession, in the Ohio valley) don’t look so much Roman as Mayan.
html http://touringohio.com/history/jeffers-mound.html
http://touringohio.com/history/marietta-earthworks.html
http://touringohio.com/history/newark-earthworks
http://touringohio.com/history/seip-mound.html
http://touringohio.com/history/art/seip-earthworks—2.jpg
The best evidence for Romans in America is the Bay of Jars wreck, which went down by Rio de Janeiro about 1800 years ago. Some nitwits claim that the jars were “salted” onto the site by an Italian guy in the 1960s, but since the jars have been coming up in fishing nets since the 1850s, apparently his greatest achievement has been the invention of a time machine.
http://www.freerepublic.com/focus/chat/3295687/posts
http://www.freerepublic.com/focus/news/1038045/posts
http://www.freerepublic.com/focus/bloggers/1248340/posts
This beauty was found in a precolumbian Mexican tomb, and the only thing that could be done about it was denial that it was found in the tomb.
http://www.econ.ohio-state.edu/jhm/arch/calix.htm