Petra, Jordan: Huge monument found 'hiding in plain sight' Published duration 10 June 2016

image copyright ILaBianca/ JBlanzy image caption The outline of the monument can be seen from the sky (l), the other image shows some of the detail

A huge monument has been discovered buried under the sands at the Petra World Heritage site in southern Jordan.

Archaeologists used satellite images, drone photography and ground surveys to locate the find, according to the study published in the American Schools of Oriental Research.

The large platform is about as long as an Olympic swimming pool and twice as wide.

Researchers say it is unlike any other structure at the ancient site.

The study, by Sarah Parcak of the University of Alabama, Birmingham, and Christopher Tuttle, executive director of the Council of American Overseas Research Centers, describes the find as "hiding in plain sight".

image copyright QTweissi image caption Ground surveys played their part in the discovery too

Petra dates back to the fourth century BC, when it was founded by the Nabataean civilization, who inhabited parts of what is now Jordan, Iraq, Syria and Lebanon.

Surface pottery suggests the platform was built in the mid-second century BC, when Petra was at its peak.

It is thought the structure may have had a ceremonial purpose.

The survey also revealed a smaller platform was contained inside the larger one, which was once lined with columns on one side with a vast staircase on the other.

media caption Petra, the city carved in stone

Mr Tuttle told National Geographic that someone in decades of excavation "had to know" the structure was there yet it had not been written up.

"I've worked in Petra for 20 years, and I knew that something was there, but it's certainly legitimate to call this a discovery."

Hundreds of thousands of tourists visit Petra each year, although numbers have been hit by the conflict against so-called Islamic State.

The site is best-known for the Treasury Building, which is carved from sandstone and featured in Indiana Jones and the Last Crusade.

image copyright AFP image caption Petra's most famous landmark is the Treasury Building