It is the most impressive of the preserved Mycenaean tholos tombs, situated at Mycenae, on Panagitsa hill.
The walls of the chamber and the long dromos (36 m. long and 6 m. wide) are lined with conglomerate ashlar blocks. The tholos or round chamber (h. 13.20 m., diam. 14.20 m.) is roofed with a conical corbel vault, having the shape of an old-fashioned beehive. A distinctive feature of the tomb is the side-chamber hewn in the rock (6 x 6 x 5 m.).
The rich sculptured and painted decoration that once ornamented the facade (10.50 x 6 m.) is not preserved on the monument. Between two half-columns of green stone with carved motifs, the entrance (5.40 x 2.45-2.70 m.) had a wooden double door set in the inner side of the long stomion (5.40 m. long) which was sealed with accumulated stones. A decorated plaque was placed on the "relieving triangle" over the lintel, which was made of two enormous granite slabs (the inner measuring 8 x 5 x 1.50 m.).
The "Treasure of Atreus" was constructed in ca. 1250 B.C. and was in use for a long period, not precisely defined.
The tholos is made of thirty-three superposed rings of conglomerate ashlar blocks, perfectly fitted so that each slightly projected beyond the edge of the one below it.
The monument remained visible and had already been plundered when it was mentioned by Pausanias (2nd century A.D.) as "Treasure". For a while it was used as a refuge by shepherds whose fires blackened the walls of the tholos. In 1878 P. Stamatakis cleared the dromos and the chamber. Of the relief decoration of the facade only fragments detached by Lord Silgo and Lord Elgin have survived in various museums (Munich, Karlsruhe, Berlin and especially, London and Athens).