The archaeological site of Nan Madol is one of the most interesting attractions on Pohnpei Island. Construction of Nan Madol was started in the 8th, or 9th century, during the peak of the tyrannical Saudeleur dynasty and it was the dynasty's capital until 1628. The ancient stone city was scattered over some 100 artificial islets off Phonlei's southeastern coast. Most buildings were made from stacked basalt pillars.

The largest remaining structure is Nan Douwas. The outer walls of the compound stand are 8 m (25 feet) high and the inner compound contains interesting burial crypts. Many other temples, vaults, bathing areas and pools have collapsed, but ruined Nan Madol is still quite impressive.