"It is amazing we got it built,” says architect Brad Cloepfil of his design for the National Veterans Memorial and Museum (NVMM), which recently opened on the banks of the Scioto River, in Columbus, Ohio. Now, nearly six years after his firm, Allied Works, won an invited competition for the $75 million project, Cloepfil still seems incredulous—largely because of the 53,000-square-foot building’s demanding structure. The roughly circular NVMM comprises a series of exposed concrete arches that are curved in plan and overlap to create three intersecting rings and a spiraling circulation path, both inside and out. The behavior of the unusual form was tricky to analyze, and its construction was labor-intensive, according to Thorsten Helbig, a partner of Knippers Helbig, the project’s New York– and Germany-based structural engineer. The poured-in-place structure was so challenging that, after participating in a design-assist phase, the preselected concrete contractor declined to bid on the building’s construction. It took two months to find another qualified contractor. “I had never designed a building that no one wanted to build,” Cloepfil says wryly.