It is a common assumption that anything older than a few centuries must be incredibly rare and, consequently, exorbitantly expensive. When beginners to historical collecting discover that they can purchase an authentic, 1,600-year-old Roman coin for the price of a cup of coffee, they are often met with disbelief. How can a tangible piece of the mighty Roman Empire—held by citizens, soldiers, and merchants millennia ago—cost around or less than £10? next...