The Sanctuary of Poseidon at Kalaureia, located about 5 km from Poros Town, is one of the island’s most important ancient landmarks. Dating to the 6th century BCE, this Doric sanctuary was dedicated to Poseidon, god of the sea, and served as the meeting place for the Calaurian League, a federation of city‑states including Aegina, Epidaurus, and Athens.

Although only foundations and scattered stones remain today, the site offers a peaceful, open‑air experience with panoramic views of the Saronic Gulf and the Peloponnese coast. Informative plaques provide historical context, and the surrounding pine forests create a tranquil atmosphere for visitors interested in Greek history away from the crowds.

👉 Visit in the early morning or late afternoon when the light is soft, making both the ruins and the gulf view especially photogenic.