From the ground level, the U.S. Capitol dome appears much like it did almost 150 years ago, but up-close inspection reveals an aging icon in desperate need of restoration. While the dome is designed to match the appearance of the stonework used on the Capitol building itself, the structure is comprised of 9 million lb of painted cast iron. With its prominent position overlooking the National Mall, the building's massive metal dome has been battered by the elements for decades, leading to significant corrosion and deterioration of hundreds of decorative elements. Even more troubling, more than 1,000 cracks have been documented during inspections in recent years—with some allowing moisture to penetrate to the interior.
After years of paint and seal work to help slow the damage, Congress appropriated three years of funding, starting in fiscal 2013, to launch the $60-million Capitol Dome Restoration project. In September 2013, a joint venture of Turner Construction and Smoot Construction was awarded the project, and work got under way the following month.