The Space Needle, a defining landmark of Seattle’s skyline since 1962, has been undergoing a $100 million renovation.

On August 3, it unveiled its latest addition: the world’s first and only revolving glass floor, known as “The Loupe.”

Standing 500 feet — or 50 stories — above street level, the observation deck’s new see-through floor offers 360-degree views over the northwestern US city.

The floor is powered by 12 motors and, as reassurance to the faint-hearted, is constructed of 10 layers of tightly bonded glass.

More than a million guests already pass through the Space Needle annually, with the new attraction sure to bring in a fresh rush of thrill-seekers.

Fifty-six years after the Needle was built for the 1962 World Fair, the futuristic structure’s even more futuristic facelift is taking place under the guidance of Olson Kundig — with the original architect’s blessing.

Walls, barriers and entire floors have been replaced by clear structural glass to expand views.

The floor of the rotating restaurant SkyCity is set to become glass as well, and is set to reopen in 2018.