Ancient Egypt: Great pyramid of Giza lopsided 'thanks to building error'

The great pyramid of Giza may be slightly lopsided, with its west side slightly longer than its east side, scientists have discovered. For many years, scientists have tried to get exact dimensions of the pyramid, but it is the first time they have realised that its original base may not have formed a perfect square.

The oldest seventh wonder of the ancient world – and the only completely intact - the great pyramid of Giza is a prowess of human engineering which is even more impressive given it was constructed some 4,500 years ago. The construction work is believed to have been finished in 2560BC under the rule of Pharaoh Khufu – a king of Egypt's fourth Dynasty.

However, the pyramid's appearance has changed quite a bit in the past centuries. When it was first constructed, it was clad in 21 acres of white stones casing, but most of it has been taken down over the years and reused in other construction projects.

This has made it harder for scientists to accurately measure the pyramid as it originally stood and to determine whether its features were created to be as perfectly balanced as they looked.

Looking for the casing stones

The latest attempt to obtain the pyramid's original measurements was initiated by a team from the Glen Dash Research Foundation and the Ancient Egypt Research Associates (AERA) – which has been mapping and excavating the Giza plateau for the past three decades.

To determine the lengths of the original pyramid sides, the scientists looked for surviving casing stones situated at the foot of the pyramid's platform, and which would have formed the pyramid's original casing baseline.

The also looked for marks on the platform such as etched or cut lines in front of the casing stones to locate where its original edges had once been. One of the lead authors, Mark Lehner, identified 84 points along 155 metres (508 feet) of the pyramid's periphery where he found evidence of the baseline and of the original edges.

Data mapping

The scientists processed the fresh data in a grid system that they had previously used to map out all of the features of the Giza Plateau. The way this grid system works is by assigning every point on the plateau an address, with the origin of the map at the centre of the Great Pyramid. Everything is then measured from that central point.

Based on the mapping of the marks and the remaining casing stones, the researchers were able to project the original lengths of the pyramid's base.

Their results indicated that the east side of the pyramid originally measured between 230.295 and 230.373 metres (755.561 and 755.817 feet), while the west side of the pyramid originally measured somewhere between 230.378 to 230.436 metres (755.833 and 756.024 feet). So the west side was probably a bit longer than the east side, but no more than a few centimetres.

The researchers are not certain how the Ancient Egyptians built the Great pyramid of Giza so they are not exactly sure where this slight measurement error comes from, but it could be the result of a mistake made during the construction.

Nevertheless, it does not take away from the fact that 4,500 years ago, Ancient Egyptians already possessed very advanced technical skills which made the remarkable construction of the pyramid possible.