Ostia Antica from Fiumicino

I bet a taxi would be your best bet to get there. It would certainly be the fastest way. I'm just not sure how you would get back to the airport. I don't recall any taxi stands at the ruins.

Michael is partly correct. I am not aware of any direct connection to OA and you have a problem with luggage. Not sure if there is luggage storage available at the airport. Have not seen it but have not looked for it either. I think the easiest solution would be to take a taxi - fixed at 45E - to Termini, use the left luggage area -- lower level, right side of station as you enter. Take public transit to OA, very easy to do, return at your convenience, claim luggage and go your apartment. There is a little cafeteria within OA which is OK for a quick lunch. Otherwise the area is more like a big park and nothing much around it.

I agree that food options are extremely limited in and around Ostia Antica.

The short answer is that there's not an option that is really cheap AND convenient AND fast. You can pick two out of those three. :-) I seem to recall that a cab ride from FCO to Ostia Lido is about 20E. It should be about the same to Ostia Antica. You can always ask the driver first. He should certainly know how much it would cost. There is also the option of taking a Cotral bus from FCO into Ostia Lido, then hopping the train to Ostia Antica (only a couple of stops). Or you could taxi to Ostia Antica, then when done, train from OA to Ostia Lido where you would hop on a bus back to FCO. The thing I don't like about Frank's option becomes apparent when you look at a map. FCO is right next to OA, so the idea of going all the way into Rome just to double back doesn't appeal to me. (Also the train from Termini to OA involves two separate trains at two separate stations.) And it turns out that there is a left luggage at FCO, so that opens up some options.: http://www.luggageguides.com/articles/1350/left-luggage-facility-rome-fiumicino-airport.html And the cafeteria at OA is perfectly fine, but gluten free might be a bit of a challenge in the land of pasta. Good luck.

I think it would also be easier to go on to the Termini in Rome and put your bags in the storage locker/or room, and then take local transportation to Ostia Antica, and then return at your convenience. Now, the last time I was there, in 2009, I enjoyed it but I took a subway to Ostia Antica and a subway back. That way it left from the Termini Square and then returned to the same place. Here is the link to look at from Rick Steve's
http://www.ricksteves.com/plan/destinations/italy/ostia.htm Hope this helps. Have a good trip.

I still think my earlier suggestion, same as Jerry's, is the easiest and simplest but your cannot take the subway to OA. Does require a change at Piramide. It is one metro ticket buy two for you have one for the return trip. Take line B from the lower level of Termini to Piramide. It is a surface exit turn left and follow signs to Ferrovia Roma-Lido which is next set of tracks. The stops should be shown on an overhead panel in the car. Get off prior to Lido Nord. Don't remember the exact name of the stop but OA is in the name. The train runs all the way to the beach at OA and if a hot day there will some attractive young Romans on board. Reverse coming back to Rome.

The train stop on the Roma-Lido line is actually called "Ostia Antica" per the ATAC map on their website. (Sometimes the stops for ruins will have the word "Scavi" in their name - it means excavations.) And it is definitely two different lines from Termini, as Frank says. Good luck with whatever option you choose. Ostia Antica is pretty cool. Here's a great website for it: http://www.ostia-ostie.net/indexEN.html