Barack Obama and Michelle Obama climb Sydney Harbour Bridge without safety ... trends now

Former US president Barack Obama and his wife Michelle have been given special permission to climb Sydney Harbour Bridge without safety harnesses. 

The casually-dressed couple scaled the world-famous landmark on Wednesday as they prepared to leave Sydney to continue Mr Obama's speaking tour in Melbourne. 

The Obamas and their entourage were allowed to walk over the 'Coathanger' without having to wear the jumpsuits and safety apparatus usually required by operator BridgeClimb.

A spokesman for BridgeClimb referred inquiries to Transport for NSW, stating that authority had 'facilitated' the visit, which included the Obamas' Secret Service minders.

The Obamas arrived about 10am before ascending 1,332 steps along the arch and standing 134m above the water with 360 degree views of the harbour.  

After completing the walk, Mr Obama was seen accepting a souvenir BridgeClimb cap and talking to workers clad in high-visibility clothing.

Other world figures to have climbed the bridge include Prince Harry and Crown Prince Frederik and Crown Princess Mary of Denmark.

Oprah Winfrey, Will Smith, Matt Damon, Nicole Kidman, Kylie Minogue, Justin Timberlake, Cameron Diaz, Robert De Niro and Pierce Brosnan have all reached the summit.

On Tuesday night Mr Obama gave a broad-ranging address to a sold-out crowd inside the International Convention Centre at Darling Harbour.

The 61-year-old received a standing ovation from the 9,000-strong audience who heard him reveal reveal he once had a 'crush' on a Qantas flight attendant.

As well as the sell-out crowd, around 500 people tuned into the talk online, with tickets to buy a link to the stream selling for around $400.

Those who wished to hear Obama speak had to dig deep into their pockets for a ticket, with a standard fare coming in at just under $200.

The event's 'platinum package', which cost $895, featured a welcome cocktail at a one-hour drinks function, commemorative lanyard and signed copy of Mr Obama's memoir.

With a further 10,500 to see Mr Obama talk at a Melbourne event on Wednesday night, he could be up for a payday upwards of $1 million.

Mr Obama opened his first talk by hailing Sydney and describing his love for the city.

'Sydney is fantastic, we have had such a wonderful time here, it's one of the world's great cities,' he told the audience.

Discussing his first time visiting the city an eight-year-old, he said: 'I was travelling from Indonesia where my mother was living at the time, to my grandparents in Hawaii and I was travelling unaccompanied.'

'We had to stop for a day for the connecting flight and Qantas stewardess took very good care of me. I had a big crush on her.

'I felt very sophisticated, very worldly, travelling on my own and so that's my first association with Sydney.

'And it just keeps getting better every time I come back.'

The rapturous reception Mr Obama received on Tuesday night followed complaints earlier in the day from Sydney residents who objected to his huge 'nuisance' motorcade.