Treasury of Atreus

Dating back to around 1300 BC, this is the finest existing example of a domed tholos (Mycenaean tomb shaped like a beehive). It's wonderfully misnamed, since it probably has little to do with Atreus or Agamemnon, but the interior is truly awe-inspiring, with a 40m-long passage leading to the vast beehive-shaped chamber, with evidence of the powerful door that once sealed the tomb.