The stone city of Nan Madol is built of natural basalt "logs". Some are 30 feet long and weigh over 50 tons.

The construction used at Nan Madol creates an inward pressure on the walls and keeps them standing. Long basaltic logs were placed end to end, with coral rubble between them. The short cross-pieces were laid so that the inner end rests on the coral rubble with the other end on the outside log.
Nothing prepared us for what we saw. The trip to Nan Madol was one of the greatest experiences we have ever had.
Charles and Julie Feinberg
In the rear, there is an underground hole that holds several people - and can be covered with a flat rock.
Nan Madol is truly out of this world ... this was the most unique and enjoyable vacation we have ever taken. Now that we’ve been here, we will be back.
Mark & Sandra Fredricks

Only the Saudeleurs were allowed to use the main entrance. Commoners showed respect by crawling on hands and knees through holes in the walls.

The oral history of Pohnpei says that Nan Madol was built by two brothers - Olosipa and Olosopa. According to an old story, these brothers sailed their ships along the coast of the Americas, and traded with the natives. When trading was finished at the equator, the westward sail across the Pacific was difficult because the ships couldn’t carry enough food and water for the trip. Was Nan Madol only a watering station