As a bevy new construction rises around it, the iconic US Bank Tower in Downtown Los Angeles is not resting on its laurels. In fact, with the upcoming opening of its thrilling new 47,300-sq-ft, Skyspace LA, the current tallest building west of the Mississippi is pushing the architectural envelope.

"We are part of a project that allows all Angelinos to get a vantage point on LA that was previously only for executives on the top floors of the tallest building," says John Adams, project principal for Gensler, which designed the observation decks for Skyspace LA. "This project takes a mono-functional office building and creates something that is not just for work, but is also for play and a different kind of experience."

The project, which opens to the public on June 25, is highlighted by California's highest open-air observation deck, and a thrilling exterior glass slide between the 70th and 69th floor. Located 1,000 ft above the city streets, the Skyspace LA project offers 360-degree views of the Pacific Ocean and much of Los Angeles County, and as Adams notes, it allows the public a unique aerial perspective of Downtown and the sprawling metropolis beyond.

The slide was designed by Brooklyn-based engineering firm M. Ludvik & Co., while Gensler created the two, 2,500 sq-ft observation decks and associated interiors across four levels, including an outdoor terrace on the 69th floor, an elevator transfer floor and a lobby area.

Audrey Wu, Gensler project architect, told me that to fully take advantage of the views, they designed an infinity edge for the roof terraces "so you have the sensation of the edge just dropping off and you are just separated by a plane of glass with 1,000 ft below you."

The edges of the observation terrace are lined with seven-ft- high, low-iron glass balustrades that visually disappear. Similar to the slide, only a plane of glass separate visitors from the 1,000-ft drop.

And speaking of being separated by a plane of glass, I got to try out the new slide before it opened to the public and it doesn’t disappoint. Made with stainless steel and 1.5-inch-thick triple-laminated hurricane glass, the 45-ft-long, fully enclosed, all-glass slide is a bit hair-raising. But if you are afraid of heights, there is always an elevator or stairs.

As part of their work, Gensler also redesigned the building's 54th floor with an infinity mirror floor "opening," and a giant picture wall that takes photos of guests and pixelates them into a dissolving, "Star Trek" like image.

Another architectural highlight is the Monumental Stair on floor 69. This gravity-defying showpiece features a custom center stringer, triple cantilevers, floating treads made of 1" think steel plates and Italian quartzite and low-iron glass guardrails cantilevered off the sides of the treads with high-strength blackened stainless steel.

The US Bank Tower, which was built in 1989, is owned by OUE Limited, a diversified real estate owner, developer and operator.