This partially restored temple to the goddess of the hunt dates from approximately 420 BC, with some earlier remains. Most remarkable is an ancient stone bridge over the river (now rerouted), cut through with wagon-wheel tracks. Entrance is via a very good museum, which shows remarkable votive gems and statues of children (Artemis was their protector). Then a pleasant path leads to the site through lush marshland with lots of birds. Another path leads to a quiet stretch of beach.
From Athens, take metro line 3 to Nomismatikopio, then bus 304 to Artemis (Vravrona). It’s a 10-minute taxi ride from there.