Paestum has an amazing complex of three temples and amphitheatre a couple of hours drive from Naples.
The temples are better than Athens Acropolis IMO but the setting is not as spectacular.
It was great to walk around as there wasn’t huge crowds.
See for yourself:
The three temples are dedicated to Hera, Athena and Poseidon. Not too many people worship them anymore but once they were considered universal with powers over everyone.