Two thoughts. This place was less than 10 miles from Delphi, a day trip to the oracle and the nearby markets. I wonder if there will be any information related to the relatively unknown sea peoples and that period of history.
This is a tholos tomb, of which something like 100 have been found at various places in Greece, the largest ones being at Mycenae. This one has some grave goods that were not robbed in antiquity (not unique--the tholos tomb at Vapheio yielded two fine gold cups showing scenes involving bulls, and a suit of bronze armor was found at Dendra, one of the tholos tombs near Mycenae).
For tombs to be found in this ruined condition with the upper levels gone is also not unique. It looks from the photo that perhaps larger stones were placed in modern times on top of the surviving top level of the stone, presumably for protection, since the lower levels have smaller stones.
The “relatively unknown sea peoples” are for all practical purposes a modern fiction — no tombs, no graveyards, no graves, no towns, no geographic traces, no characteristic weapons, no characteristic pottery, no coins, no nothin’.