Tomb of Eurysaces the Baker, Rome
I went for a run one morning in Rome and this was around the corner from our place. It was so unusual, and remarkably, unmarked. You know, just another ol' hunk of something in Rome. I looked into it and discovered it's a funerary monument dating back to 50-20 BC, honoring a BAKER! How cool is that? Wikipedia has a nice article about it here if you care to learn more.
This was just one of the many things about Rome that blew me away...to have something so old and so cool around the corner without even a sign. I suppose when the Colosseum is down the street, this is small potatoes. I absolutely loved my time in that magical city and I can't wait to go back.