According to studies, the island seems to have been inhabited since the Bronze Age. Specifically, the tombs that have been discovered date from the Mycenaean Period while other finds on the island exist from 1000 BC. Equally important is that excavations at the end of the 19th century at the top of the hill, in the area where the ancient city of Kalavria was located, found ruins of a temple dedicated to the god Poseidon. Additionally, In Poros in 322 BC, the ancient orator Demosthenes, was poisoned with hemp, after escaping capture by Antipater (governor of Macedonia). Also, on Vagionia beach, the ancient port was found in the sea. Notably, according to Strabo, Poros was part of an alliance, also known as Amfiktionia, with the cities of Athens, Aegina, Epidaurus, Hermione, Trizinia, Nafplio and Prasia. In particular, a huge celebration, depicted on a plaque, which shows the celebration of the revival of this alliance, which dates back to the Hellenistic Period, was found in the ruins in the area of Kalavria. During the Byzantine Period, many pirate raids were made in Poros. Then during the Turkish occupation the island remained independent. Important to realize is that the island’s participation in the fight for independence, during the Greek Revolution of 1821, was dynamic. To clarify, the island offered live material, ships, money and great personalities such as the Christodoulou brothers, Georgios Kriezis and Georgios Mertikas. Finally, the leader of the fight, Giannis Davaris, died and was buried in Poros.