East Attica area includes both mountain and sea. Mountain Ymmitos or Hymmetus separates the area from the city of Athens. In Peania, you can also discover a cave, the only you can visit in Attica, the Cave of Koutouki which was discovered in 1954.
The length of the cane is approximately 350 m and the internal temperature is at 17 degrees. It was open to the public at 1960’s. Ticket price is 2 euros and visiting hours are from Monday-Sunday 08.00-15.00. Guided tours are available from 08.30 and the last one is on 14.30. You can call for more info at +302106642108 or find it at google maps here.
Coastal areas start from Marathon, continues to Nea Makri, Rafina, Porto Rafti, Artemida and Lavrio with its ancient mines. Also east Attica landmarks are really close to Athens airport, so they are suggested for few hours trips. There are quite a few landmarks you can visit, such as:
Amfiareion and Oropos area: A former wealthy attica area, with an archeological site, dedicated to Amfiareion. The site was the central exchange point with Euboea and later destroyed by Christians.
Marathon Tomb: The place where the 192 dead Athenians were buried, after the Marathon Battle of 490 BC.
Marathon Dam: The dam that provided water to Athens. It was built between 1926-1929.
Attica Zoological Park: A place where you can spend time with your family https://www.atticapark.com
Porto Rafti: A place that you can combine a dive at the sea but also seafood, at a local tavern.
Vravrona: a famous archaeological site, as for the temple of Artemis, next to Porto Rafti bay. There is also an archeological museum there, worth visiting.
The place is atmospheric and unique.
Vravrona tower: a medieval tower, left from Athens Latin occupation.
If you want to go southern, here are some nice spots.
Lavrion: ancient mines of silver that funded Athens’ navy are located here. There is also a museum.
Thorikos: another archeological site.
Sounio: the famous Poseidon temple, marks the last point of Attica.