For a fascinating history lesson, check out the crumbling remains of Temple of Poseidon and picture how it looked in its heyday.
You're spoiled for sightseeing choice when spending time in Poros. Temple of Poseidon is an ideal place to begin here, but there are loads of other fine sights to enjoy. Askeli Beach, Poros Town Clock Tower, and Kanali Beach are close to the once-important structure and and will cap off your day nicely.