Flatiron Structures Company, founded in 1970, has grown from a division of a local paving company into a national construction company specializing in heavy civil and transportation projects, including specialty bridges. Headquartered in Longmont, Colorado, the firm began its growth working on significantly larger and more complex projects in Colorado, including the construction of a series of projects in the Glenwood Canyon corridor of I-70. Flatiron received national recognition for its work in Glenwood Canyon, and in addition to other awards, was awarded the American Concrete Institute's Project of the Year.

Today Flatiron is building some of the most challenging projects in the country. In Boston it is working on two significant Central Artery/Tunnel contracts: the South Boston Interchange West and the I-90 Logan Airport Interchange. The firm is also working at Logan International Airport rebuilding the elevated terminal area roadways. On the West Coast, Flatiron is leading joint ventures for the seismic retrofit of the Benicia-Martinez Bridge and construction of the new Carquinez Suspension Bridge, both in the San Francisco Bay Area.

Flatiron Civil has recently completed the Sagadahoc Bridge in Maine, North America's longest span precast segmental structure and Maine Department of Transportation's first design-build project. In South Carolina, the firm is working on the design-build of the 20-mile Carolina Bays Parkway, a new highway whose alignment is adjacent to the Intracoastal Waterway.