The term 'Citadel Athens' refers to the Acropolis of Athens, an ancient citadel located on a rocky outcrop above the city of Athens in Greece. The Acropolis is a UNESCO World Heritage Site and is home to many ancient monuments, including the Parthenon. The Acropolis was built in the 5th century BC and served as a fortress and religious center for the people of Athens. The two crossword solutions for this term are DONAT (5 letters) and COED (4 letters). DONAT is an acronym for the Doric Order of Architecture, which was used in the construction of the Acropolis. COED stands for co-educational, which refers to the fact that the Acropolis was open to both men and women.