Answer:
Thebes was located in the Greek region of Boeotia, in central Greece. To the Southeast, we find the region of Attica, a small peninsula were Athens was (and is) located.
Attica is connected to the Peloponnese (the large peninsula that comprises the southernmost part of the Greek mainland) throught the Isthmus of Corinth. As the name implies, in this Isthmus, the ancient city of Corinth was located, as well as the city of Megara.
In the Peloponnese, there were many cities and villages, but two of the closest, geographically-speaking, to Thebes were Mycenae, Argos and Tegea. A bit farther inland, Sparta was located.