The Arch, six metres high and created from Roman limestone, was restored after developments in technology made it possible to insert an invisible steel support structure inside the37-tonne work.
Unveiling it in Kensington Gardens, Colin Buttery, deputy chief executive of the Royal Parks, said they had always wanted it back but had long feared that it would not prove possible.
Hi-tech scans at Imperial College in 2004 revealed the source of the problem and pointed to a solution."
