Petralona Cave is situated at a distance of 50 Km. from Thessaloniki. The cave was discovered at random by locals of the Petralona Village looking for groundwater. In 1960, a skull of a man between 25-35 years old was discovered, a very old man for the standards of the primitive era. The skull belongs to a type of archanthropus (that is of a standing man) in a transitional form between Homo erectus to Homo sapiens neandertalensis. The fossilised skull is a finding of utmost significance from an anthropological aspect, yet has not been finally classified unanimously according to the experts. According to paleoanthropologist Aris Poulianos, the skull is considered to have belonged to a man who had lived 700.000 years ago, whereas the fire traces are 700.000-1.000.000 years old and are the most ancient traces ever to have been discovered on earth up to nowadays. Many tools made of stone and bones were also unearthed, along with fire traces which he used to warm up and bake his food.