An archaeologist claims he has finally solved the mystery surrounding the Great Pyramid's peculiar alignment after spotting a "flaw."

The Egyptian expert believes he has the answer to how the ancient civilisation was able to build the complex structure, despite lacking modern technology.

Researchers from US-based Glen Dash Research Foundation and the Ancient Egypt Research Associates (AERA) previously identified a "flaw" in the alignment.

A popular theory suggests the 4,500-year-old structure, which is estimated to weigh over six million tonnes was built after huge stones were moved from a nearby quarry, dragged and lifted into place.

The Great Pyramid was built 4,500-years-ago

Experts discovered that three sides of the pyramid's base were once between 230.295 metres and 230.373 metres long, but the west side came in between 230.378 metres and 230.436 metres – meaning it was off by about 14.1cm, reports the Express.

However, the sides fit perfectly despite the measurements, along with the cardinal points of north, south, east and west, with all three of the largest Egyptian pyramids – two at Giza and one at Dahshur – remarkably aligned.

Archaeologist and engineer Glen Dash said: "All three pyramids exhibit the same manner of error, they are rotated slightly counterclockwise from the cardinal points.”

Many hypotheses exist as to how the ancient workers did this, including using the pole star to align the pyramids or the Sun’s shadow – but Mr Dash claimed he had cracked the mystery.

An archaeologist believes he has solved the mystery surrounded the Great Pyramid

His research, published in The Journal of Ancient Egyptian Architecture, suggested that the Egyptians used the autumnal equinox to achieve perfect alignment.

The Earth is tilted on its axis, meaning that as it orbits the Sun, the star illuminates the northern or southern hemisphere more depending on the orbit.

However, at two points in the year, the Sun will illuminate the northern and southern hemispheres equally, in what is known as the equinox.

Ancient civilisation was able to build the structures without modern technology

The expert also showed the degree of error was similar to that found in the alignment of the Khufu and Khafre pyramids at Giza, and the Red pyramid at Dahshur.

Despite the convincing argument, there is still no solid evidence that it was the case.

Mr Dash concluded in his report: “The Egyptians, unfortunately, left us a few clues.

“No engineering documents or architectural plans have been found that give technical explanations demonstrating how the ancient Egyptians aligned any of their temples or pyramids.”