We had only a short stay at the Gem Society during our layover in Athens, but already based on that can recommend this place. The room was clean, spacious, quiet and had an AC. The hotel is located near the Monastiraki metro station and thus easy to reach from the airport. The acropolis is within walking distance. The highlight, the secret gem (pun intended) of this hotel, however, was their incredibly tasty moussaka. Do not miss it!