A fresh view of Sydney icon

FOR the first time, visitors to Sydney can climb their way into the "cathedral of steel" at the heart of the Harbour Bridge.

Inside view ... the new Discovery Climb through the Sydney Harbour Bridge celebrates the bridge's remarkable engineering. Picture: Jeanti St Clair

FOR the first time, visitors to Sydney can climb their way into the "cathedral of steel" at the heart of the Harbour Bridge.

The company behind the city's popular bridge climb today launched a different route to the top of the engineering marvel.

Visitors have been able to climb over the top of the bridge's main arch for some time, but the new Discovery Climb passes through the lower suspension arch before ascending to the summit.

It allows climbers to touch the huge rivets and sturdy steel girders of the bridge, which will be 75 years old on March 19.

Visitors pass the point where the two halves of the bridge were first joined, before climbing steep steps to a platform on top of the bridge, 134m above the harbour.

Guides can now take people across newly-accessible catwalks to parts of the bridge that have never been open to the public before.

Paul Cave, founder and chairman of BridgeClimb Sydney, said the new tour offered a "very different" experience from the original bridge climb.

"With the original bridge climb you are on top of the bridge with the sky as the ceiling," he said.

"With Discovery you are right within the bridge itself. You get a much better sense of the steel, the rivets and the engineering design genius."

Although it took several years to solve all the Discovery Climb's safety and logistical problems, Mr Cave hinted at further developments in the future.

"There will be other climb experiences. But we need to solve lots of issues to make each climb happen," he said.

The bridge climb has attracted 1.8 million climbers since starting in 1998.

The two climbs would attract several hundred thousand visitors this year and on some days in December and January would operate 24 hours a day, Mr Cave said.