Located in the Venetian Resort in Las Vegas, Sphere bills itself as “The future of boundary-pushing entertainment,” redefining the live entertainment experience with immersive technology. But its wow factor gets people even before they step inside. Its architecture is awe-inspiring. It’s the largest spherical structure in the world. And, steel is largely responsible for this record-breaking achievement.
Designed by global event space architect Populous with consulting engineers Severud Associates and Walter P Moore, Sphere reaches 34m high and spans 157 metres wide and its exterior is clad in a high-resolution LED screen, which wraps around its curved steel hollow structural section (HSS) exosphere. This means that the colour and images on Sphere can be changed to anything that can be dreamt up. Since its completion in 2023, it’s been a giant yellow smily face, as seen above, a vast eyeball and a carved pumpkin, amongst a host of other iterations.
A feat of hollow structural section (HSS) steel engineering
“This required a framing system that could support complex geometry, precise tolerances and large-scale integration challenges that ultimately pointed to steel, and in many areas, to hollow structural section (HSS) steel,” explains Holly Schaubert, Director, HSS, Steel Tube Institute.
“The team relied heavily on steel and, particularly, on HSS, which were central at every level. The building integrates three distinct HSS systems or layers: an interior layer supporting the fully immersive wrap-around 16k display, the structural exosphere and the exterior lattice layer supporting the exterior LED display made up of 1.2 million puck lights.”
By using HSS, the project team was able to deliver the clean lines, tight curvature and structural performance necessary to support the immersive media experience inside and out.
Steel met the architectural and structural demands of Sphere
“Steel was chosen for the Sphere,” says Schaubert, “because no other material could as efficiently meet the combined structural, architectural and media integration demands of the project. The structure required a system capable of handling complex, multi-directional forces while supporting two massive LED display systems, all within a spherical architectural form.
“A concrete shell, as an example, would have introduced excessive dead load and would have been far more difficult to form and reinforce with the precision required. Steel, by contrast, allowed for a lighter structural system with a far higher degree of control over curvature and connection geometry. HSS were used where torsion performance, multi-axis loading, curved geometry, aesthetics and connection efficiency were critical.”
The spherical diagrid of the exosphere was formed from round HSS, creating the primary outer shell that supports the exterior LED surface. A second layer of HSS was then used on the exterior to support the LED light pucks mounted to the exosphere. Within the structure, a lattice of rectangular HSS was used to suspend the interior LED screen, minimising framing depth, while delivering consistent strength under combined bending and axial loads.
Steel adapts to the Las Vegas climate
“Across all systems, the closed shape of HSS provided uniform performance and aesthetics and worked seamlessly with cast steel nodes, which connected members at complex angles with high precision,” says Schaubert. “Structural physics played a central role throughout. The steel systems had to account for thermal expansion, seismic movement, and wind loads, particularly across the curved exosphere. For example, engineers designed exterior components with pre-deflections to absorb anticipated thermal shifts — avoiding misalignment of LED elements during Las Vegas temperature swings. Multi-directional load paths through the HSS diagrid and interior support frames were carefully modelled to ensure structural performance under a range of conditions.”
To make these systems buildable, each HSS member was precisely fabricated off-site, cut to length, hole-punched and test fit before being shipped for final assembly on site. Connections were made using custom-cast steel nodes, which were digitally modelled to match the geometry of intersecting members with tight tolerances. While the Sphere’s steel systems were not fully modular, they were installed in a carefully sequenced manner, relying on the predictability and consistency that HSS allows. This approach ensured that the structural frame aligned precisely with the architectural skin and media elements.
Visible from miles away, the Sphere is now an iconic part of the Las Vegas skyline, a first-of-its-kind venue that merges immersive technology, structural engineering and public spectacle.
Steel is helping set a new precedent for what large-scale entertainment architecture can achieve.