Page "Great Pyramid of Giza" Paragraph 4

The pyramid remained the tallest man-made structure in the world for over 3, 800 years, unsurpassed until the 160-metre-tall spire of Lincoln Cathedral was completed c. 1300.

The accuracy of the pyramid's workmanship is such that the four sides of the base have an average error of only 58 millimetres in length.

The base is horizontal and flat to within ± 15 mm.

The sides of the square base are closely aligned to the four cardinal compass points ( within 4 minutes of arc ) based on true north, not magnetic north, and the finished base was squared to a mean corner error of only 12 seconds of arc.

The completed design dimensions, as suggested by Petrie's survey and subsequent studies, are estimated to have originally been 280 cubits high by 440 cubits long at each of the four sides of its base.

The ratio of the perimeter to height of 1760 / 280 cubits equates to 2π to an accuracy of better than 0. 05 % ( corresponding to the well-known approximation of π as 22 / 7 ).