"This monumental platform has no parallels at Petra or in its hinterlands at present," the researchers wrote, noting that the structure is only half a mile away from the city centre but "hidden" and hard to reach.

The structure consists of a massive platform, measuring 184x161ft (55x50m), roughly the size of two Olympic swimming pools side by side, with an interior platform that was originally paved with flagstones. In the middle of the smaller platform sits a 28ft square building facing a row of columns and a staircase to the east.

Pottery recovered from the site dates to about 150BC, and the platform’s design has no parallels to any other structure in the ancient city, the archaeologists say in the paper.