Originally Posted by platbrownguy
You should get an invitation when you check in... IIRC, the OA lounge and Aegean lounge are right next to each other - the OA lounge was livelier and nicer overall (this was a while ago).
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I think you are referring to the Schengen departures area, not the International non-Schengen area. There is an OA lounge in each of these areas, but there is an A3 lounge only in the Schengean area.