Greece is the land of the gods! Literally! There are temples and statues to Greek mythology almost everywhere. Athens is great to start with because you can just walk the streets of Athens and see temples to Zeus, Athena, Poseiden, etc. Of course, visit the museums in Athens for more statues. The best two are the Acropolis Museum and the National Archaeological Museum. Then outside of Athens, the temple of Poseidon at Sounio is great and Delphi where the oracle resided. Some islands of interest are Naxos with a temple to Apollo and Delos island is replete with ancient temples to the gods.