The feature is subject to amateur speculation, which has been argued to be hagiography (refers to the biographies of saints and ecclesiastical leaders by serious scholars), especially suggestions that it was constructed by an unknown civilization, Egyptians, South Americans, or the Chinese.
Rex Gilroy claims that he discovered the Gympie Pyramid in 1975 and claimed that the "Pyramid" was created by Egyptians who had mining operations in Australia centuries ago, with bases of operation reaching as far as the Blue Mountains in New South Wales. In his article on the subject, Anthony G. Wheeler writes, "It seems that a terraced hill was claimed to be a pyramid on the basis of a nearby stone wall around a church being of unusual construction, supposed local legends and taboos that warned against intrusion into the pyramid area, the predominance in the area of a cactus of South or Central American origin, a statue (the 'Iron Man' or 'Gympie Ape') of non-aboriginal manufacture found nearby, and some crude inscriptions on a stone block dug up in the area." Wheeler notes that an amateur archaeologist, Marilyn N. Pye, became convinced that the "pyramid" and other features were evidence of ancient settlement in Australia by the Incas of South America.
While Pye argues the "pyramid" is of Incan origin, Gavin Menzies states that it is "direct and persuasive evidence of the Chinese visits to Australia" and that "its size, height and shape are typical of Ming Dynasty observation platforms and it would have been wholly logical for the Chinese to build observatories to determine precisely the location of the phenomenal riches they had discovered."
Wheeler argues that the claims of an extraordinary origin for the pyramid are unfounded, writing, "The facts are (probably) that the Gympie "Golden" pyramid is actually an ordinary hill terraced by early Italian immigrants for viticulture that has been disfigured by erosion and the removal of stone from the retaining walls for use elsewhere ... As for all the supporting statements by the various authorities, all but a few unimportant ones fade away as one after another proves to be a misquote, a falsification or an outright fabrication."
Currently the Queensland Department of Main Roads is planning to build a road through the site.
The Gympie Pyramid has been researched independently and found to be far more banal. It was part of a retaining wall built by an Italian farmer to stop erosion on a natural mesa on his property.
Significant work on the origin was undertaken by a Gympie historian, Dr. Elaine Brown, during the 1990s and early 2000s in which she found that the terraced structure was constructed by a Swiss horticulturist in the late 1880s.
Sourced from Wikipedia
More info can be found here http://www.bibliotecapleyades.net/esp_australia01.htm