By Ian Simpson
WASHINGTON (Reuters) - The rebuilt cast-iron dome of the U.S. Capitol, a soaring symbol of national unity since the 19th century, was formally completed on Tuesday after a $60 million overhaul that included repairing rust-choked gutters and more than 1,300 cracks.
The project was the first complete rehabilitation of the 288-feet-tall (88-meter-tall) Civil War-era dome since 1960. It was finished in time for the inauguration of President-elect Donald Trump on Jan. 20.
"It is the symbol of American democracy and a beacon of hope around the world, and we delivered," Architect of the Capitol Stephen Ayers said at a news conference.
The structure tops the home of the U.S. Congress and can be seen throughout the capital. The Capitol is a major tourist site, drawing thousands of visitors daily.
When work began in January 2014, the dome was suffering from water leaks, cracks and corrosion so bad that rain gutters were clogged with rust chips, Ayers said. Up to 13 layers of lead-based paint were removed and 666 feet (203 m) of cracks were repaired.
Ayers, who was flanked by workers and executives, said the project relied on sophisticated software to keep track of repairs and used 3-D modeling to cast replacement parts. The structure is believed to be the biggest cast-iron dome in the world, he said.
Illustrating the fine detail involved in the repair work, officials displayed a fist-sized decorative acorn made up of seven parts, all of which had to be designed and replaced.
Repainting required a total of 1,215 gallons (4,600 liters) of paint, with the top of three coats in the color "Dome White."
The dome was completed during 1861-65 Civil War and President Abraham Lincoln viewed its construction as a symbol of the nation's endurance during the conflict, the bloodiest in U.S. history.
Ayers said the work, which was funded by Congress, uncovered traces of the original construction process. Pieces of iron were stamped with the name of supervising engineer Montgomery Meigs, a crowbar from the era turned up, and a name - Al Ports - was found written in plaster, he said.
(Reporting by Ian Simpson; Editing by Frances Kerry)