When I did Classics A Level (quite a while ago) it was composed of three sort of "areas" of study.
You had epic poetry, tragedy (plays), and art & architecture.
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For epic poetry we studied two books -
One was Homer's The Odyssey which is an ancient Greek book about Odysseus (A Greek hero) trying to get home after having been at the Trojan War. He has many adventures along the way and meets all sort of mythological creatures and different people, etc.
The other was Virgil's The Aeneid, which is a Roman book about Aeneas, a Trojan hero, who leaves Troy after the war and heads off to Italy and ends up founding Rome.
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For tragedy we studied a few plays. I forget all of them - I know we did Oedipus, Medea, and Electra but I forget if there were any more.
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For art & architecture we studied some temples, some statues, and some pots / vases