The scaffolded US Capitol is seen at sunset on October 28, 2014 in Washington, DC with a compass marker in the walkway looking West. The US Capitol dome will undergo its first comprehensive repairs in more than half a century this autumn, installing a donut-shaped canopy to protect visitors to the historic structure. The two-year, USD 60 million project is aimed at repairing nearly 1,300 cracks that have emerged in the nine-million-pound (4.1-million-kilogram) cast iron dome, according to the Architect of the Capitol (AOC) office. Construction on the dome began in 1855. Work symbolically continued through the US Civil War and the structure was eventually completed in 1866.