The cyclopean ruins of Nan Madol in Pohnpei, in the Caroline Islands

The archaeological enigma of the "ghost site" in the archipelago of Micronesia, made up of about 100 small artificial islets connected to each other by a network of canals, has bewitched "mystery investigators" over the centuries, from Irish sailor James O'Connell to Colonel James Churchward, to neuropsychiatrist Oliver Sacks.