Roma Pass

You would have got a quicker response had you posted in the Italy forum. To answer your question, buy the pass in Rome. You can find the pass at the TIs at the airport and train station.

Thank you so much.

You can easily buy one in Rome. Only takes minutes if you go to a place without long lines. (Don't buy at the Colosseum itself!) On Ron in Rome's excellent post about the pass he says "I suggest against purchasing online because you're not sent the packet. Rather, you are given a "code" that you have to take to specific "pick-up points." Now, if one of these is convenient to your hotel or B&B, then yes, this can be an effective method for you. But more often than not, these pick-points are not. And many do not open until 9 or 9:30 AM! So do know that if you purchase online you WILL NOT walk off your plane with a packet in hand." Read more here http://www.roninrome.com/transportation/should-i-buy-a-roma-pass including a list of places you can buy your pass. (This list is also on the Roma Pass website.) I beleive the R.S. Guide says you can even buy them at some Tabbacchios, like the one near the Colosseum. (I didn't go look this up so it might be wrong.) FWIW we bought ours at the Palatine Hill entrance, as Rick also suggests, and it was only about a 10 minute line.

According to people on the Trip Advisor Rome Travel Forum, the online purchasing of the Roma Pass was not available due to technical difficulties. It's easy to purchse when in Rome. It's definitely worth it.

We got our RomaPass at a tabacchi store on Via Cavour across the street from the Forum. The tabacchi stores that sell them will have a sign posted outside the store to indicate they have them. If you buy your pass at a store, you can use it on the metro on the way to your first sight. They do run out of passes, we got ours at the 2nd store that we tried.