Guess where this is!
UDATE: Several of you got this right. Its the entrance to the the Treasury of Atreus, which is also called the Tomb of Agamemnon. Both those labels are false, as it's older than both Atreus and Agamemnon. It was a royal Mycenaen tomb build, incredibly, in 1250 B.C.
The inside is amazing. And the stone above the entrance weighs 120 tons. http://j.mp/OelWjbhttp://en.wikipedia.org/wiki/Treasury_of_Atreus