When I started out on this whole journey, I honestly did not think I would end up in Athens. It just seemed (and still seems) extremely surreal to me. It's very insane to me that I accomplished going to a place that was always a "oh one day" place. You know the kind, "oh, one day I'll visit this list of places" and you never actually do. Or you're too old to enjoy living in crappy hostels and rooming with people you've never met.
As a history major (and a person who was obsessed with the Greek gods when I was younger—no I don't know why), I figured I'd just end up in England and travel all over to these places. That was how it was going to go, too, until one of the professors shoved this catalog under my nose one day. She told me that I should check out this program that schooled/housed people in Athens for a semester or a year and you got to visit all the ancient sites. I applied, got in, and in a matter of a few months was on a 20-hour trip to Athens, Greece with my roommate and best friend.
The Athens International Airport is a bit insane. It's kind of like one of those rinky dink airports that you see in small towns. It's very lax in construction and the Customs area is a tad unorganized. Good news for EU people, you apparently just get to glide straight through the line. Bad news for us non-EU'ers: you will have to wait at least an hour and a half to get through customs. (Oddly, the reverse is true on the return trip. I literally just walked up to the customs booth, handed him my passport, said hello, and he stamped me through and pointed me in the right direction. No questioning or anything.). There are MANY taxis waiting outside of the airport, and most of the drivers speak English. Also, never, EVER get into a taxi unless it is a yellow, conventional looking taxi. Those guys will take your money and drop you off in the middle of nowhere. You will need at least €12 to get out of the airport area and into downtown Athens, probably another €12 to €20 if you are going anywhere else. There is also a metro (subway) system and a bus system, which are cheaper, but I do not suggest using either, unless you a.) know where you are going or b.) have amazing subway skills. On the metro, you will be pushed towards the center of the metro and you need to be able to push your way out when you get to your stop. The stops are read in Greek and English, so you're good there. The bus is a tad scarier, and if you have a ton of luggage, I don't suggest getting on there. Both take about 45 to 60 minutes to get to downtown. The buses run until midnight and start again at 4 or 5 in the morning. The metro runs until like midnight, but doesn't start up again until 7 or 8am. That should be all the info you need for the airport!