Prusa ad Olympum, a settlement in south Bithynia was not a remarkable city throughout antiquity. It did not attract attention even its name is mentioned with the relentless enemy of Roman Republic, Hannibal of Carthage. Our knowledge about how the city looked like is very limited, if some orations of one of its citizens, Dion Chrysostomos are excluded. Very few authors mention it with very few sentences. Some authors confuse it with other cities carrying similar names, while others repeat what previous authors had written. Two authors, Strabo and Pliny the Elder express genuine views on the foundation of Prusa but they claim different founders and ages. According to Strabo it is founded by a Prusias who made war against Croesus, king of Lydia, while Pliny said it to be founded by Hannibal, who took refuge to king Prusias I of Bithynia. Since a founder named Prusias, contemporary of Croesus is unknown, attempts have been made to correct Strabo’s sentence and Pliny is regarded as the correct source for the foundation of Prusa. However to make a fair judgment it is necessary to analyse the lives, styles, sources and historiography of two authors. Such an analysis leads to the conclusion that Pliny's statements about Prusa should be approached more skeptically. He is not considered as a reliable source on history and geography, the natural sciences sections of his work attracted more attention. Since Plinius' credibility was seriously damaged, the possibility that Prusa was founded in the 6th century BC should be reevaluated in the light of new findings.