Tips for a Vacation in Rome, Italy

Rome, Italy is a truly beautiful city, and a very worthy destination for people of all ages. After having spent four days in Rome, and a couple weeks outside of Rome, I've learned a few things that would, in my mind, be helpful tips for anyone else following in my footsteps:

1. Wear tennis shoes or comfortable shoes. You have to walk—a lot—if you really want to see and enjoy Rome. The metropolitana (Rome's subway lines) only covers the northern parts of the city, and a few ancient ruins.
2. Get a good map of the city; there is an illustrated map that you can find at almost any hotel/touristy area which shows pictures of all the major sights, and has every street marked. Even a GPS won't do so well in certain parts of Rome.
3. Bring a light camera, unless you're a stock photographer. With all the walking, you won't want to lug around a huge digital SLR and a bunch of glass if you don't have to. The memories are what counts - there are thousands of beautiful pictures of every sight in Rome - no need to take more of those pictures! A smaller, lighter camera affords more mobility, meaning you see more places.
4. Don't get caught in one or two ruins—i.e. don't tour the Colosseum or the Forum unless you really, really really want to. It's better to walk to another destination than to get caught in a four hour tour of a place in which you're not that interested.
5. Try the gelato. Seriously. Every chance you get, stop in a gelato shop. There are some especially good ones near the Via Merulana and across the Tiber from Castel Sant' Angelo.
6. If someone approaches telling you they have a special tour, or cool bracelets, or anything, ignore them. Don't even look at them. If you let them hook you in, you'll have to work to break yourself free from their sales pitches. (Also, don't look too 'touristy' if you can avoid it, at least not in the 'touristy' areas where street vendors are hanging around like vultures).
7. Don't get your picture taken with a gladiator or a mummy or any of the 'interesting' people around tourist sites. You'll be asked to pay up afterwards, usually to the tune of €5 or more!
8. Always pack an umbrella (get a little purse umbrella if need be) - rain is very random in Italy, and it can come at a moment's notice. If there are no clouds in the sky, don't carry the umbrella with you, but have one just in case. You can always buy one for €2-5 from a shop on the streets.
9. If you can figure them out, use the buses - they are very convenient if you need to get somewhere fast, or if your feet are worn out.
10. Try to speak a little Italian, even if you don't know much! Usually, even Italians who don't "parle" English will get the idea. The most important words:
    1. Parli inglese? --> "Do you speak English?"
    2. Ciao. --> "Hello."
    3. Grazie! --> "Thanks!"
    4. Prego. --> "Thanks," "You're welcome," and pretty much anything.
    5. Buongiorno/Buonasera/Bunanotte --> "Good morning/evening/night!"
11. Places you must visit: The Colosseum (at least look at it), St. Peter's Square, St. Peter's Basilica, the Vatican Museums, Piazza Navona, Via del Corso (walk along the fancy shopping street and end at the Spanish Steps / Spagna), Trevi Fountain (just to see it), St. Paul Outside the Walls (if time allows), Termini (it's like the Italian Penn Station), every Gelateria you see, the Pantheon.
12. Places you could visit if you have time: All the awesome columns and Egyptian obelisks around the city (you could play a game and see who can find them first), the four Major Basilicas (St. Paul Outside the Walls, St. Mary Major, St. John Lateran, and St. Peter's), any other Church in the city, the Forum, the Circus Maximus (you can walk around it and act like you're Ben Hur ;-), Castel Sant' Angelo, Catacombs, the Scavi Tour (exclusive tour of the catacombs under St. Peter's - sign up early!), the Scala Sancta ('Sacred Stairs'), the Trastevere (Piazza di Santa Maria especially).
13. When eating, be sure to not ask for ketchup, burgers, salad dressing (they only use vinegar), or candy bars. You're in Roma! Enjoy the fish, the pasta, and the pizza... and most especially, the gelato! Crepes are also a nice way to finish off a meal. Ask for water senza gas (meaning without bubbles) or naturale—unless you'd like to try the gassy water ;-)

Any more tips? Leave 'em in the comments, please.