Nan Madol was an ancient city of Pohnpei where the rulers known as the Saudeluer Dynasty used to live. It was a place for both cermonial and political seat for the Saudeleur Dynasty. The Saudeleur Dynasty was the period of the first rulers of Pohnpei uniting the people of Pohnpei, ruling from the 1100 to around 1628. After the era of the Saudeleur Dynasty a new period preceded by the Nahnmwarki. The Nahnmwarki era started when the Saudeleur was overthrown by Isokelekel, another mythical foreigner who became the first Nahnmwarki in Pohnpei. Source: https://en.wikipedia.org/wiki/Nan_Madol
Here is a link to the history of Nan Madol by the U.S. National Park System. Source: https://www.nps.gov/places/nan-madol.htm
Here’s a link below to another site in Lelu, Koasrae Federated States of Micronesia one of the four states located east of Pohnpei. Some people claim that Lelu site is connected to Nan Madol because they have similar stone constructions to the ones in Nan Madol. For more in formation click on this link: Lelu site on Kosrea FSM.