The Heidentor, in modern-day Austria - also known as Heathens' Gate or Pagans' Gate - is a partially-reconstructed ruin of a Roman triumphal arch, situated in modern-day Austria.  In an ingenious display, a line diagram of the rest of the structure has been etched onto a sheet of perspex, allowing visitors to stand in front of it and line it up with what still stands in front of them, to appreciate the triumphal arch would have looked in its full glory.

Learn more about the Heidentor and some other examples of innovative virtual reconstruction of monuments here.