Engineering the 7 New Wonders: Petra

First came the 7 ancient wonders, but once their glory faded, the world selected a new group of wonders that stand with unmatched engineering prowess. This is the Lost City of Petra.

You may know the stone city of Petra from Indiana Jones and the Last Crusade, but its marvel extends far beyond this short cinematic glory. The city of Petra is actually a series of city buildings built into the side of rocks, and the most famous is the Treasury building, otherwise known as Al Khazneh. Believe it or not, this city was only discovered by the western world in 1812, and the Swiss explorer who found it had to disguise himself to get past the locals.

Unlike many of the other wonders on this list, the City of Petra was carved completely out of the surrounding earth and rock. Construction is estimated to have begun as early as the 5th century B.C., so the question remains: how did this ancient civilization create an expansive carved city?

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These civilizations wouldn’t have access to any of the modern technology that makes rock carving possible. To the extent of mechanical tools, the there would have only been chisels and hammers. Engineers had to get creative to create such massive relief structures, so instead of starting from the bottom, they started construction with the roofing structures first. Once architects determined where the structure would start talented sculptors would climb to the top of the laid out structure and start carving. They would slowly, layer by layer, work their way down to the base. Workers would have used nothing more than pickaxes, chisels, hammers, all primitive tools to today’s standards. Like much of engineering today, the builder and engineers that built Petra were focused on sustainable construction. They reused nearly every bit of scrap material produced in the carving process.

Located in Southern Jordan, the rock facades on the cliffs were completely sandstone. This made carving easy, but engineers had to take into account structural loading throughout all of the construction. Beyond the construction of many of the cliff buildings, the city of Petra was located in the middle of the desert. At its peak, there were 20,000 people living there, and water was of utmost importance. Large pools in the middle of the desert were built to hold the city’s water. Long channels were used to divert water from the nearby river.

This city was built out of sandstone, yet it has survived for over 2000 years with minimal weathering. Not to be overlooked, there has been significant weathering of some areas of Petra, but the Treasury and other notable buildings were positioned to last against winds and rain.

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If you like discovery, the lost city of Petra may be a Wonder you will want to follow. Archaeologists have only discovered an estimated 15% of the entire city due to its relatively recent finding and the fact that it is cut off from modern civilization. Teams of engineers are also helping to study the lost city by using 3D scanning to discover and secrets to how it was constructed. The laser scanning revealed that the engineers of Petra carved steps into the surrounding mountains to both use a primitive and safe scaffolding as well as to reveal the rock strata they had to work with. The ancient engineers valued the lives of their skilled stone masons, so they took great care to make the construction process safe and simple.

Mysteries within this great city abound, and through the fervent research by archaeologists and engineers, we are discovering more and more about the ingenuity of ancient designs and builders.

Sources: CalvinASMEScience FocusNational Geographic

Image Sources: [1][2][3]

 

Profile photo of Trevor English
Trevor is a civil engineer by trade with an extensive background in internet media and marketing. He loves finding new and interesting topics and bringing them to the rest of the world.


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