Relative to its grand provenance and imposing figure, the Sphinx of Ramses II received a paltry welcome upon its arrival in North America in 1913. The 3,000-year-old red granite Egyptian statue languished for more than a week at the Port Richmond docks. No one wanted to move the human-headed, lion-bodied beast when the local baseball team, the Philadelphia A’s, was in the midst of the World Series. But without “brawny workmen,” in the words of the Philadelphia Inquirer, the sphinx wasn’t going anywhere: The giant sculpture weighs 12.5 tons.

Eventually, a work crew of 50, along with a cargo crane, special moving beds, and “a crowd of Penn students” relocated the mythological creature from the German freighter Schildturm to the Penn Museum’s courtyard. It spent just three years in its original location, before museum personnel moved it indoors, ultimately landing in a windowless gallery surrounded by other objects from ancient Egypt.

On June 14, the sphinx saw the sun for the first time in more than 80 years, as part of a museum renovation that will put the sphinx outdoors—and closer to eye-level with visitors. This go-round, the move took a handful of engineers less than a day to finish the job, thanks in no small part to industrial hoverboards.

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The statue arrived in America from Egypt in 1913. The Penn Museum

“I can safely say that I did not really sleep the night before,” says Bob Thurlow, the Penn Museum’s project manager.

Thurlow and his team spent months mapping out the exact path of the sphinx’s relocation and anticipating every possible moving day scenario. The first step was a feasibility study, to see if transportation was even possible. “The sphinx came into the building through a hole in the wall,” Thurlow says. But that wall closed up long ago, as the expanding museum added new buildings to its densely-packed campus. Fortunately, they were able to identify a clear, albeit narrow, passage that would allow the sphinx to slip through with just 1 or 2 inches on each side.

Next, the engineers needed to design a comprehensive route. They developed a workable plan, but “it wasn’t a straightforward pathway,” Thurlow says. The sphinx weighs about 600 pounds per square foot, so construction workers had to reinforce some of the floors along the route. Fortunately, the museum, which has spatially expanded over its 132 year history, maintains a color-coded floor plan for just such events. “It hurts the eyes to look at,” Thurlow says of the schematic, “because there are so many colors in so little space.” The team also prepared the sphinx’s courtyard landing pad, adding concrete and additional rebar beneath its resting place.

But the most important item on Thurlow’s to do list was to identify the easiest, safest way to actually move the ancient artwork.

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The Sphinx has been outdoors before. The Penn Museum

The solution: an air-filled flotation machine from AeroGo, a company based in Tukwila, Washington that makes jacks, rigging systems, and transfer carts for the airplane industry. Its website weight classes max out at 10 million pounds. The “hoverboard,” as Thurlow describes it, consists of a steel plate that sits atop neoprene bladders. When you fill those receptacles up with compressed air, they create an effectively friction-less dolly that can glide an Egyptian statue or cutting-edge plane wing to its destination. “Once you’re moving it, a single person can move it,” Thurlow says (though of course, the Penn Museum would never allow such chicanery).

The only problem is, the hoverboard is omnidirectional. Where a real dolly would follow its wheels, AeroGo’s contraption had a mind of its own. To keep it on course, Thurlow and his team ran tests to identify slopes, valleys, and pockets in the floor where the air cushion might want to float. They added ramps or fixed up floors, meticulously evening out every surface so the device would stay true to its course. They also added rails to the ramps wherever necessary, so if the archaeological parade float did veer, it would still be contained. “It makes it super easy,” Thurlow says, “if you know what you’re doing.”

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An engineer measures the hieroglyphic-covered Sphinx to prepare it for its move to the courtyard. The Penn Museum

On moving day, the team secured the statue to a rig, then lowered it onto the inflated bladders. Over the course of five grueling hours, Thurlow and the main rigger slowly guided the statue from its old gallery to its new skylit enclosure. “Every step we hit, where we got around the problem or solved the problem, there was a little pressure off our shoulders,” Thurlow says. By lunchtime, he says, their mood had improved significantly.

The sphinx successfully made it to its new resting place, but it won’t be publicly viewable until November. For now, museum staff has enclosed it in a bespoke box, to protect it from dripping paint and construction dust as workers refurbish the space around it over the coming months. Thurlow says the few people who were able to see the statue before it was enclosed were moved by what they saw on site, even though it was an object they’d seen many times before.

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The sphinx in motion. The Penn Museum

“It’s very interesting how the context changes what the sphinx is,” Thurlow says. “When it is sitting down, directly on the floor, your eyes are almost directly level with the sphinx’s eyes.” It’s imposing, but approachable, just as it would have been in Egypt 3,000 years ago, when sphinxes were seen as strong but protective, even welcoming, creatures. What’s more, you can now see details of the sphinx’s design that were obscured by its former spot, dark and elevated indoors. “It has ribs on both sides,” Thurlow says. “The back hips on it are a little twisted. It’s not a perfectly square piece.” None of these things are obvious unless you spend some time looking. Now, he says, visitors will actually get the chance to.

The sphinx has a new home, but the museum’s makeover continues. The main entrance will also be ready by November, when the sphinx makes its debut. Thurlow’s also leading the continued renovation of the Egyptian galleries, which will continue over the next few years. The museum has a palace from Memphis, Egypt, as well as a tomb chapel weighing in around 40,000 pounds, both of which will have to be repositioned. But for now, Thurlow, who leads these efforts, can breathe a sigh of relief. “I very much enjoyed working on this project, and I’m glad it’s over.”