Nan Madol is a series of more than 100 islets off the south-east coast of Pohn­pei that were con­struct­ed with walls of basalt and coral boul­ders. These islets har­bour the remains of stone palaces, tem­ples, tombs and res­i­den­tial domains built between 1200 and 1500 CE. These ruins rep­re­sent the cer­e­mo­ni­al cen­tre of the Saudeleur dynasty, a vibrant peri­od in Pacif­ic Island cul­ture. The huge scale of the edi­fices, their tech­ni­cal sophis­ti­ca­tion and the con­cen­tra­tion of mega­lith­ic struc­tures bear tes­ti­mo­ny to com­plex social and reli­gious prac­tices of the island soci­eties of the peri­od. The site was also inscribed on the List of World Her­itage in Dan­ger due to threats, notably the sil­ta­tion of water­ways that is con­tribut­ing to the unchecked growth of man­groves and under­min­ing exist­ing edi­fices.