It's easy to hop on the subway and head to Athens' industrial port, Piraeus. Take a taxi to the pretty fishing harbor of Microlimano Bay, where you can join Athenians looking for a cool evening outing or a good seafood restaurant.
Afterward, spend the evening in an open-air cafe or in one of the area's lively nightclubs. Piraeus also has a few other attractions, including a good Naval Museum and an Archeological Museum. Most people simply pass through Piraeus to board cruise ships or hydrofoils to the islands.
5 mi/8 km southwest of Athens.