While Marcel Breuer's beloved—and sometimes derided—1966 design for the Whitney Museum could feel like a fortress for artwork, Renzo Piano's recently completed structure eschews any notion that it stands apart from its surroundings.

"A building for culture should be open and accessible, unintimidating and unpretentious," Piano says. "You don't see the limit between the street and building. You can see out, you can see the traffic, you can see the pedestrians—it's part of the city."

Heading west down Gansevoort street, visitors are welcomed with a glass wall. This Whitney wants to invite you in. And while architecture and design aficionados could praise Breuer's structure for its subtleties and materiality (the concrete work is exquisite) there's no denying its imposing stature. The lobby—or piazza as Piano dubbed it—encourages a free-flow of people in and out of the building and a dialogue between the city and the institution. Even the outdoor spaces encourage people to survey the cityscape: exterior stairways connect the sixth-, seventh-, and eight-floor exhibition spaces and terraces offer ample room al fresco. Surely the catwalks overlooking the High Line will become favorite vantage points for selfie-stick toting tourists.

Inside, viewing areas flank the galleries. They're outfitted with comfy couches and floor-to-ceiling windows, offering space to take in the sights and a way for natural light to enter the galleries. Breuer used windows to elegantly frame the Upper East Side and provide small glipses of the city beyond the museum. These take a bolder approach and pump up the drama.

The structure used over 4,000 tons of steel in its framing, which was engineered to allow the flexible gallery spaces to be free of support columns. "It's a building filled with possibilities for artists, critics, and scholars," says Adam Weinberg, the Whitney's director.

The freewheeling ethos of American art and culture undoubtedly influenced the design. "I grew up in Europe with a great gratitude for the history, but at the same time, the need and desire to have rebellion and freedom," Piano says. "The art you see is about freedom. I hope you will feel the building is designed to follow that."

The Whitney Museum opens to the public May 1, 2015, with the inagural exhibition "America Is Hard to See."