Flickr: Dr. Neko

One of New York City’s most iconic buildings – the Empire State Building – is undergoing a $120 million facelift. The project will not only restore the long-lost golden lobby ceiling, but it will also improve the energy efficiency of the building.

The skyscraper’s 6,500 windows provide a huge opportunity to make the building more environmentally friendly. Refurbishing the windows will be a vital part of the 40 percent energy savings the makeover is expected to bring to the Empire State Building. By refurbishing the existing windows, instead of replacing them, the thousands of panes of glass will be kept from wasting away in a landfill.

“We’re taking them out, breaking the seals, inserting a mylar sheath, and then we’re resealing with krypton argon gas and reinstalling them. All of this will be done without the windows ever leaving the building,” Anthony Malkin, who heads the company doing the window renovations, told NPR.

A project of this magnitude will set the standard for future skyscraper window renovations, and Malkin has agreed to share any new techniques he and his team develop at the Empire State Building.

The refurbishing project will also recreate the Celestial Mural on the ceiling of the building’s lobby. The mural was designed to honor the Machine Age and pay tribute to the technology that made it possible to build the skyscraper in just over one year in the early 1930s. The ceiling has been hidden for decades after being covered and almost completely destroyed during an effort to modernize the building in the 1960s. Both the building itself and the interior decor of the lobby have been designated as landmarks by the New York City Landmarks Preservation Commission. Since 1986, the Empire State Building has been a National Historic Landmark.

Currently the third tallest building in the country, the Empire State Building is also New York City’s tallest building. It regained this title after the terrorist attacks of September 11, 2001 destroyed the World Trade Center towers, which had dethroned the Empire State Building as the city’s tallest building.