There are several efficient ways for getting into the center of Athens from the Athens International Airport, whether or not your flight had a coupon or not. A …yellow river of taxis will be waiting outside to take you to your destination, but if you have a late arrival keep in mind that taxi rates are doubled between midnight and 5:00 am. You may also take the Athens metro, which leaves every half hour and takes about 50 minutes to get to the city center. The Suburban Railroad leaves from the same station but takes a different route, so be sure you get on the right train! You can also use the Athens Metro or the Suburban Railway if you are headed to the port of Piraeus. There are also 24-hour buses that go to key destinations. There is the X95 that serves the route, airport - city center, which goes directly into the center of Athens at Syntagma and leaves every 20 minutes. It takes around 50 minutes or so, depending on traffic. Buy your ticket from the booth outside arrivals at Athens International Airport and validate it upon entry onto the bus. You can take the same bus back to the airport at the same location where it dropped you off.