LONDON — Restoration specialists mended an arm that had been broken for 100 years on the statue of Admiral Horatio Nelson in London’s Trafalgar Square, as part of a refurbishment of the monument completed yesterday.

The statue was covered with scaffolding during the three-month project that cost $772,000.

Nelson led Britain’s naval defeat of France at the Battle of Trafalgar in 1805, and his statue towers over the square that is one of London’s most visited sites. Stone experts cleaned grime and removed copper bands used to secure the arm after it was broken by lightning about 100 years ago.

“We leave Nelson looking much better than he has for many years,”Adrian Attwood, who worked on the project for David Ball Restoration Ltd., said in a statement.

Workers made the repairs with Craigleith stone from Scotland, the same sandstone used to craft the 169-foot statue from 1839 to 1843. The monument was built to a design by Edward Hodges Bailey, who won a public competition for the project.

Workers used steam cleaners and abrasives to remove the grime from pollution and pigeons. The bronze lions at the foot of the column also were cleaned.

The city commissioned the work, and Zurich Financial Services AG paid for it.

Mayor Ken Livingstone has made a series of changes to update the square. In September, he oversaw the installation of “Alison Lapper Pregnant,” a 12-ton sculpture of a naked, disabled, and pregnant woman, on a pedestal that had long been empty.