This column's recent exposé on the pyramid-shaped structures strewn across a paddock in the Lanyon Valley (Why these metal pyramids are in a Tuggeranong paddock, August 27) resulted in a bulging mailbag.
Despite clearly dismissing suggestions by some that they were out of place tank traps, or even aircraft beacons, several readers "found it hard to believe" that the tetrahedrons (the ones with four sides, and sometimes called a triangular pyramid) and octahedrons (yes, eight sides) were part of the formwork from the construction of the triagrid ceilings at the National Gallery of Australia in the late 1970s early 1980s.
