Article: The earliest evidence of the presence of human ancestors in the southern Balkans, dated to 270,000 BC, is to be found in the Petralona cave, in the Greek province of Macedonia. All three stages of the stone age (Paleolithic, Mesolithic, and Neolithic) are represented in Greece, for example in the Franchthi Cave. Neolithic settlements in Greece, dating from the 7th millennium BC, are the oldest in Europe by several centuries, as Greece lies on the route via which farming spread from the Near East to Europe.

Now answer this question: Evidence of the earliest humans were found in what subterranean formation?
Petralona cave