America's Priciest Home.

After nearly a decade of design and development work, what is being billed as “the world’s most expensive home” is finally ready for its close-up. Set on a five-acre parcel in the posh Los Angeles enclave of Bel-Air—and aptly named The One—the 105,000-square-foot property’s interiors have remained a closely guarded secret. Until now. A.D. has been an exclusive look at what’s inside this record-setting property—and the design and aesthetic minds that made it happen.

Surrounded on three sides by a moat and a 400-foot-long jogging track, the estate appears to float above the city. Completed over 80 years—and requiring 600 workers to build—the home was designed by architect Paul McClean and interior designer Kathryn Rotondi, who were enlisted by owner and developer Nile Niami to help it live up to its reported $340 million price tag.

“This project felt exciting and simultaneously intimidating,” says McClean. But the home’s impressive site and his long-standing relationship with Niami persuaded McClean to not just take on the project but “create something unique and spectacular.”

And McClean certainly has delivered.

With its 26-foot-high ceilings, the home’s main entrance leads to an array of gathering areas with panoramic 360-degree views of the Pacific Ocean, downtown Los Angeles and the San Gabriel Mountains. The entry area is filled with water, along with a sculpture and bridge. “Water is something we often use in our design process because it allows for a sensory change that helps you adjust to your surroundings,” says McClean.

The use of black, white and gray throughout the home was based on Niami’s desire to have a neutral palette that would allow the landscape and panoramas to shine.