A while back I had a conversation with a fellow forumer and he scoffed at the notion that the Polynesians could have possible have had any notable civilization of their own. That reminded me of a documentary on the islands of Nan Madol, which are part of Micronesia, in the middle of the Pacific.
It is a group of 92 man-made islands, which are made of stone probably transported by sea, and on which there are massive megalithic structures dating to the 12th century AD. Archeologists believe that the structures had a religious purpose, and that they show a high degree of organization.
http://en.wikipedia.org/wiki/Nan_Madol
The islands were abandoned by the time of the European conquest. Later on, they inspired H.P. Lovecraft to create his mythical land of Chtulhu.
These islands together with the much better known Easter Island and the Polynesians' remarkable nautical skills, are in my opinion, proof that the Polynesians are underrated in world history.