I was on holiday, really. In fact, I only left the hotel once. But I’d been told I couldn’t come back without seeing the Temple of Poseidon. Byron went. He said:

Place me on Sunium’s marbled steep,
Where nothing, save the waves and I,
May hear our mutual murmurs sweep;
(from Don Juan, Canto the Third - LXXXVI) 

It’s a bit busier nowadays, but the view over the Aegean at sunset is pretty impressive. As are the fifth-century BC doric columns.

See the full Cape Sounio gallery here.