It's no secret that Rome is a city chock-full of the ancient past. Reminders of a city, and empire, of 2,000 years ago aren't just rife in the Forum, Palatine and Colosseum, but beneath churches like the Basilica of San Clemente and San Nicola in Carcere, acting as the main event in open spaces like the Park of the Aqueducts, and even serving as forums for everything from ballet and opera to light shows and displays. In short, ruins are everywhere.

Maybe that's why some of my favorite ancient ruins in Rome aren't the big, famous monuments. They're the little bits of antiquity that you simply stumble across: an ancient column sunk into the wall of an otherwise-unassuming apartment building, a still-running fountain with a wornaway face that you just know must be 2,000 years old. These can be tough to find. That's part of the fun.

Here, I'll share with you my favorite "secret" bits of antiquity, tucked into street corners and buildings all across the city.

Can you guess where—and what—they are?

I've now published all of the guesses in the "Comments." To see how close you were, scroll to the bottom of this page for the answers!

Ready? Set? …Go!

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Answers:

1) I started off with a stumper: This elaborate ancient column is at the Via della Maschera d'Oro and Vicolo di San Simeone, located in ancient Rome's Campus Martius. No one quite knew what this one was!

2) A couple of you got this. This is a detail of the lovely Arco degli Argentari, or "Arch of the Money-changers," commissioned by the local money-changers and merchants who were active in the area's Forum Boarium. The arch, which was finished in 204 A.D., was built in honor of Emperor Septimius Severus, as the inscription—just to the right of the bas-relief of Hercules holding a lion skin—says. In the 7th century, the arch was incorporated into the Church of San Giorgio in Velabro.

3) This one was tricky, but it's one of the coolest ruins around. This is—wait for it—one of ancient Rome's fire stations. Truly. In particular, it's the barracks for Brigade VII, and dates back to the 2nd century A.D. The brigade was in charge of not only preventing and extinguishing fires, but public safety, too, particularly at night. It's located at Via della Settima Coorte, 9, in the heart of Trastevere. (When you go, bring a flashlight to look through the grille underneath: You can still see one of the big rooms of the barracks).

4) This is a piece of the Virgin Aqueduct, the famous aqueduct built by Agrippa in the 1st century B.C. and that supplies water to the Trevi Fountain. Believe it or not, this original piece is just off Via del Tritone; turn on Via del Nazareno, at the Burger King, and look down and to the left.

5) Yep, this was a "duh"… but it was so pretty I had to put it in. This lovely ancient column is located on Via Margana, just a few steps from Piazza Venezia.

6) Lots of you got this. This is a big chunk of the 4th century B.C. Servian Wall, located at the Termini train station (if you go inside Termini, you'll see more of it in on the lower level, including a big piece by the McDonald's).

7) These ancient columns and frieze are sunk into the building at Via di Capo di Ferro, 31, just off the Piazza della Trinità dei Pellegrini.

8) An ancient portal on Via Margana, in Rome's Rione XI of Sant'Angelo, just a few steps from Piazza Venezia.