CHARLOTTE—In 2010, the Charlotte skyline changed forever with the introduction of the 768 foot tall Duke Energy Center.  The building creates a nightly light show, and a lot of conversation.

A couple of times a year, people look up and gasp as they watch two people come off the top of the building and wash the windows all the way down. For the first time, a TV News crew was allowed on top of the building to show you the unique crane that makes it work.

                                                                            BUILDING DETAILS:

• Construction started: February 28, 2006

• Opening: January 2010

• Cost: $880 million

• Roof Height: 786 ft (240 m)

• Floor count: 48 floors (54 in total with mechanical floors)

• Floor area: 1,500,000 sq ft (140,000 m2)

The building is the second-tallest building in Charlotte, but the largest in terms of square footage.  Keeping it clean requires a high-tech machine and a lot of nerves.

"I love it. Great view," said Curt Radkin, Sustainability Strategist with the Wells Fargo Properties Group. 

Ardkin took Time Warner Cable News atop the building to show us how the crane-like device in the so-called Sky Window works.

"We call it a B.M.U., Building Maintenance Unit. It's a glorified word for a window washing unit," said Radkin. "The unit rides around on a track. The boom extends and rotates up and down. They wash windows on the way down and then it hoists it back up."

This is a one-of-a-kind unit in Charlotte.  From start to finish, it takes about two and a half hours to get down washing all of the windows, and about 30 minutes to get back up. Macedonia Polacios and Victor Estrada are two of only a handful of people who have scaled the "Power Tower", on the outside of the building. 

They took one of our cameras and took some videos:

"It's a job, just like any other," said Estrada.

While most of us would be petrified to step near the ledge, they have no problem going over it.

"What I'm scared of is when its really windy and we're way up high," said Polacios.

The washers add the toughest windows to clean are the slanted ones at the top.  They add they get a lot of support all the way down with fans inside the building.

"Yes, lots of people wave hello to me," said Polacios.

It takes about six weeks to get around the entire building. They do it twice a year, and never in bad weather.

"I really like cleaning windows, I've always liked this job, I now have 15-20 years working in this," said Polacios.

When the building was first designed, it was supposed to be the corporate headquarters for Wachovia.  When it was sold in 2008, Wells Fargo took ownership of the building.  They still own and operate it today.  Duke Energy is the main tenant in the building.