Giano Arch (Arch of Janus)
This arch is really amazing. It is the only remaining 4 arched monument left in Rome. It once lead the way for cattle ranchers, as well as provided shelter from the inclement weather for the same people and animals. As a gateway for the cattle market, this monument may seem small. This wasn’t the only monument to help in cattle trade either, as for the other temples closer to the river here designed for a similar reason.
To see the arch and surrounding structures, know that they are free (just don’t go past the gates) and pictures are allowed too.