The structure is considered mysterious by some, mainly because it is often said that one man assembled the entire structure. Leedskalnin seems to have gone to great lengths to ensure that he was not observed working. The Castle's official site states that "Ed did much of his work at night by lantern light. The Coral Castle has numerous lookouts along the Castle walls that were designed to help protect his privacy."
There are various theories that hold that Leedskalnin constructed the Castle using some unknown form of science. For example, one website claims that "Ed Leedskalnin left behind the blueprints of nature, a Secret Knowledge of the Ancients." Such theories seem to discount evidence such as photographs which exist showing Leedskalnin working apparently using traditional methods like block and tackle.
There is, however, skepticism as to the success of the traditional methods of tripods equipped with pulleys and chains that are in the photographs of Leedskalnin working. Skeptics point out that the tripods appear to only rise about 20 feet while the largest stones are 25 feet long and stand vertical. The tripods are made from wooden telephone poles and could not support the larger stones. There are not enough pulleys to lessen the weight of the stones enough that a 100-pound man could exert enough force to lift the stones. Too many pulleys will actually be counterproductive because of increased friction. The 3/8" thick chains that can still be found in the Tool Room of the Castle Tower and which are seen in the photographs are only rated with a 3.5 ton workload and would not be able to support the weight of the stones.
The Coral Castle site states that "if anyone ever questioned Ed about how he moved the blocks of coral, Ed would only reply that he understood the laws of weight and leverage well." He also stated that he had "discovered the secrets of the pyramids," which of course could be interpreted in either esoteric or engineering terms.
The Coral Castle site claims that "(Ed Leedskalnin) has baffled engineers and scientists!" However a skeptical website claimed that "despite the information on their Web site, the Coral Castle information booth was unable to identify a single scientist or engineer who had specifically examined the castle."