How it began
Nan Madol stands off the southeast coast of Pohnpei, in the present-day Federated States of Micronesia. UNESCO describes it as a series of more than 100 islets built with walls of basalt and coral boulders between about 1200 and 1500 CE. The International Archaeological Research Institute reports that the first artificial islets were begun by at least 900 CE, and that megalithic building in columnar basalt, the hallmark of the site, started around 1200 CE when the Saudeleur rulers established themselves.
How it works
The islets were raised on the reef and enclosed by walls. Long natural columns of basalt, each weighing up to several tons or more, were quarried from outcrops on the main island of Pohnpei and carried to the site. UNESCO notes that they were laid in a distinctive header and stretcher technique, with courses of columns set crosswise over one another. The columns were used mostly for the outer perimeter walls, and on the burial islet of Nan Dauas columns about five meters long roof the burial vault.
What changed first
The islets held stone palaces, temples, mortuaries and residential compounds, and served as the ceremonial center of the Saudeleur dynasty. UNESCO links the site to a period, from around 1,000 years ago, when Pacific island populations grew, agriculture intensified and chiefly societies developed.
What lasted
UNESCO cites the scale, technical sophistication and concentration of megalithic structures as exceptional testimony to the development of chiefly societies in the Pacific. The site remains tied to the Nahnmwarki system of traditional chiefs, under which Nan Madol is still owned and managed.
Where it stands today
Nan Madol was inscribed on the World Heritage List in 2016 and placed at the same time on the List of World Heritage in Danger. UNESCO names siltation of the waterways, which lets mangroves grow unchecked and undermines the stonework, along with vegetation overgrowth, storm surge and some collapse of walls.
