Luke Lamont hangs off skyscrapers for a living.

He is part of a team who clean windows on Melbourne high-rise buildings including the Eureka Tower, Melbourne's tallest building.

Cleaning the windows on a building that size is a mammoth task.

Highrise window cleaner Luke Lamont took this photo of a sunrise from the top of Melbourne's Eureka Tower. ( Supplied: Luke Lamont )

"Something like Eureka you can get done in a month, a month-and-a-half," he told 774 ABC Melbourne's Rafael Epstein.

However that kind of speed depends on good weather conditions.

"If you've got shocking weather it can take up to two, two-and-a-half months."

Eureka's windows are cleaned four times a year, which means Mr Lamont could spend up to six months a year just on one building.

Most of the cleaning is done while standing in a box known as a Building Maintenance Unit (BMU).

The tallest windows, though, can only be reached by abseiling from the top of the 297-metre-tall building.

The longest abseil requires working from the 92nd floor down as far as the 56th — a drop of more than 120 metres.

One of highrise window cleaner Luke Lamont's co-workers gives a thumbs-up while cleaning Melbourne's Eureka Tower. ( Supplied: Jarrad Church )

The 21-year-old said when he started the job he was "terrified of heights" but now he's much more comfortable.

"You forget you're hanging 92 floors up in the air."

Mr Lamont and his co-workers like to share photos of their workplace on social media.

"It's pretty amazing up there," he said.

One of Luke Lamont's photos taken while cleaning the windows on the Eureka Tower. ( Supplied: Luke Lamont )

"It's a great environment to work in and you see a lot of interesting things from up that high."

Sometimes what is happening on the other side of the window is just as fascinating as the city views.

"I've seen a few strange things, some of which I probably can't repeat."

Residents are told by building management when the cleaning is happening.

"Some people choose not to listen to that and still get a shock when they turn around and we're hanging on the outside."

The job is not without its pressures.

Luke's employer Briteway faces plenty of competition in the window cleaning business.

"We definitely need to perform," said Mr Lamont. "Everyone's always looking for a cheaper price."