To get a sense of how ancient ruins once looked, take a virtual-reality trip at this multimedia centre. The Tholos virtual-reality theatre takes you on an interactive tour of the Ancient Agora, Acropolis or Hagia Sophia in İstanbul. There are also temporary exhibitions on different aspects of the ancient world. It's not a tourist spot, but more a place schoolkids go on field trips; call ahead to arrange English narration.
Take bus 049 or 914 from Omonia, or the metro to Kallithea.