I will have a 17 hour layover in Paris on my way back to the states. I would land at Charles de Gaulle airport at about 5:30 pm and then fly out the next morning at 10:30. Is there a place to store luggage overnight? Or even so, will my luggage remained checked if I choose to venture out?
I'm not sure about keeping your luggage checked in at the airport the whole time but all of the train stations have massive locker areas where you can get a locker to store your bags. Lockers big enough for multiple bags of luggage. This is key for me when traveling around Europe. Especially for days when I'd check out of my hotel in the morning but wasn't leaving the city until much later in the day.
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I'm almost positive they would return your luggage to you and you would re-check it for the next flight, but you can verify that by calling your airline.
There are luggage/baggage storage facilities in Terminal 2 (close to TGV-RER station). Baggage and luggage items can be stored for a few hours or up to 90 days.