Analysis by Rossella Lorenzi
The oldest known example of a man-made structure was found within a prehistoric cave in central Greece, according to the Greek culture ministry. The structure is a stone wall that blocked two-thirds of the entrance to the Theopetra cave near Kalambaka on the north edge of the Thessalian plain. It was constructed 23,000 years ago, probably as a barrier to cold winds.
Read the rest on Discovery.