The Spheres are really two different buildings – an outer frame with an interior concrete core. The core was made with 12 million pounds of concrete reinforced by 2.5 million pounds of rebar. At the base of The Spheres, a 400,000-pound ring beam transfers the heavy loads of gravity, wind, and seismic forces from the glass-and-steel façade to columns in the floors below.

A geometric shape called the pentagonal hexecontahedron forms The Spheres’ steel frame. The Spheres’ shape is based on one of 26 known subsets of Catalan solids named for the Belgian mathematician who first described them in 1865. The building consists of elongated pentagonal modules that appear 180 times across the three spheres. By connecting each angle of the module to a centralized hub, the architects created a fluid yet modular pattern that could be repeated throughout the building. A steel fabricator in Oregon mass-produced the modules that were shipped onsite and assembled like a puzzle.