Nan Madol is a mysterious island in the Pacific Ocean with hundreds of thousands of basalt cubes that were brought there from a distance of 15 miles, some of which are greater both in their weight and dimensions than the stones of Cheops Pyramid. They are stored in high figures that look like an expeditionary stockroom. Under the stock pile of stone cubes there were underground rooms built. It's not easy to determine the purpose of this great structure. I'll try to explain this mysterious structure by describing the basic things another way:"There are underground spaces under a large amount of rock.". This is similar to Egyptian pyramids, where there are also underground spaces under a large amount of rock. Basalt ashlars are found in nature in the form of hexagonals or octagonals and are easy to mine. It's easier to pile them than to built a pyramid from them. Final efect - the energetic gain is the same as with the pyramids. A pyramid will always be thought of as a wonder of the world. A pile of stone cubes will always be just a pile, which however looks like constructively more proficient from the energetic point of view. The underground spaces were a sanctuary where people, like with other megalithic structures, were filling up their energy. In order to make this work there had to be optimal energetic overstrain created, where people would stay for a given time (same condition like with all other holly structures). In case of Nan Madol it was easy to create the overstress required, if the master builders controlled the increasing energetic value during the construction. When the optimal worth was reached, the import of cubes was stopped. It was not possible to do this procedure during the construction of pyramids because the tip of the pyramid was another energetic source. Because of this, the amount of matter in pyramids had to be given in the project of the pyramids. A curbed pyramid or a case when one governor built three pyramids during his life shows that this project sometimes failed. Satellite pyramids could be thought of as supplementation of the matter. Grave rooms in pyramids were built in some cases under the level of the terrain, in other cases above it. Sometimes there were rooms built above the ground level as well as under the ground level in one pyramid. We can deduce that situating the grave rooms was going through a development. Their location in different places showed different energetic values, which enabled greater practical benefit from them. The motivation for constructing pyramids can be explained by the fact that they were designed for the benefit of the health of the governor, not just after his death. We can also meet underground or partly underground built structures by other megalithic structures. I know from observation that a structure placed on an energetic place built under the ground level gives greater energetic value. It can be proved experimentally. Nan Madol structure had similar function as a cathedral. It was more perfect than pyramids not only by the possibility of optimally setting the energetic value, but also by the fact that more people could use the curative effect in the underground spaces. Its situation on a deserted island suggests that there was no optimal energetic location on the inhabited neighbouring islands. The energetic function of the pyramid is confirmed also by the case when Egyptian governor Amenhemed III. built sixty metres high pyramid from non burnt bricks in Basara, which was overlaid by lime plates. However, one construction feature absolutely unique to the pyramids is not possible to explain by any means. About 50 centimetres above the gabled ceiling of the grave room there is approximately 90cm thick wagon roof built from adobe bricks. From a static point of view it can't be said that the wagon roof built from adobes could have been a supporting element. The purpose of this wagon roof hasn't been explained yet. The wagon roof could have had a function of an energetic magnifier, but only when we assume that the energetic value of its matter was greater than the energy of surrounding walls. Probably that could be reached by adding another activating element to the bricks during their formation - metal or other metallic ores. January 2006