Archaeologists believe they have solved the mystery behind one of the world’s greatest wonders. Researchers from the University of North Carolina at Wilmington in the United States have found that the pyramids of Egypt, including the Great Pyramids of Giza, may have been built alongside an abandoned branch of the River Nile. Some 4,700 years after the pyramids were built, the study suggests that a lost 40-mile (64km) branch of the Nile was used to transport building materials for the structures, which took 1,000 years to complete – explaining why they are located in what is now a barren and uninhabited stretch of the Sahara Desert. “Most of us who work in ancient Egypt know that the Egyptians must have used some sort of waterway to build their monumental structures, such as pyramids and valley temples, but no one has been able to pinpoint the location, shape, size, or proximity of this navigable channel to the actual pyramid field,” said the University of North Carolina’s Eman Ghoneim, quoted in The Independent . As such, the researcher and her colleagues studied satellite images to find the location of a channel that may have run along the base of the Sahara. They then used geophysical surveys to confirm the presence of river sediments and ancient channels beneath the modern land surface. The academics believe that a build-up of wind-blown sand and a major drought that began around 4,200 years ago may have caused this branch of the river to migrate eastwards and eventually dry up. Read More: Egypt regrets lack of "will" to resolve Palestinian conflict (Portuguese version)