You should file your completed passport application at a US Post Office authorized to accept passport applications. You will need proof of US Citizenship (certified copy of birth certificate), a signature photo ID, and two identical 2″ x 2″ passport photos. Passports processing may take up to four weeks in some cases so you better take care of this well in advance.
If you already have a passport, remember to check your passport’s expiry date before your trip. Make sure it’s valid for at least a while after your planned return. However, don’t fret if your passport expires while you are on your trip – you can renew it at any U.S. Embassy in the EU within a few days time.
To get help with your passport application – just visit your local Passport Agency or one of the following websites: