For the sake of argument, lets assume that the Romans had vessels that could cross the Atlantic and that the Empire was interested in the Americas for colonization. Say that the Colony is established during the reign of Agustus and by the time of Constantine it has faded to memory, leaving the American Empire alone. If it didn't have to deal with the Dark Ages, how advanced could the colony have become by 1492 when Columbus makes his voyage? How would the American Empire react to Columbus? How would it interact with Europe?