From his airy, light-filled 38th-floor penthouse in Lincoln Park’s tallest building, Jim Gearen enjoys stunning vistas of the lake framed by 12-foot, barrel-vaulted arched windows—a reflection of the building’s mansard roof. The 4,200-square-foot space was just a blank slate when he first toured it in 2015, but his vision for the interior was just as expansive as the views.

“I spent my career in commercial real estate, and I was sort of the idea guy,” Gearen says. “I’ve worked with some great architects and built some really fun houses over the years.”

Above Jim Gearen’s beloved player piano hangs a drawing of John Lennon by political cartoonist John Kascht, one of Gearen’s university classmates.

Indeed, Gearen has built or rehabbed five other homes over the past two decades, most recently the renovation of a lakefront estate in Door County, Wis., by renowned Chicago architect Harry Weese. Interior designer Ruth Johnson had been by his side for four of them, and he soon brought her on board for this project as well.

“Ruth finishes my sentences,” Gearen says. “She’s able to work in any vernacular that I’ve thrown at her, from really hard-edge modern to this place, which has its own style.” Explains Johnson: “Jim and I share a common language and excitement for architecture and design, so it’s a collaborative, thoughtful and fun exchange.”

Eager to collaborate with new talent, Gearen also commissioned dSPACE Studio, a young, Lakeview-based architectural firm turning heads with its sleek, modernist designs. Founder Kevin Toukoumidis and principal Tom Hagerty knew from the get-go that the project could turn out to be something special. “Jim is a visionary client, and he saw the potential,” Toukoumidis says.

From top: A rug and sofa from RH Modern and a steel-and-leather chair from Scout define a casual sitting area; bronze pendants from Holly Hunt illuminate custom oak cabinetry by Steven Cabinets in Minneapolis.

But there were as many challenges as there were opportunities. Adding plumbing to the new kitchen island, for one, required them to open up the ceiling in the apartment below Gearen’s. Fortunately, the downstairs neighbors were happy to help, allowing workers to enter their unit while they were away on holiday.

The noisy cooling towers on the roof directly overhead added another wrinkle. To solve the problem, Gearen engaged a sound engineer who suspended the ceiling from sound-isolating springs, wrapped the pipes and filled the gaps with filters. The result? “Stone-cold silence,” Gearen says.

An Alison Berger pendant hangs in a small interior powder room.

To hide the exposed utility pipes in the entry foyer, the architects designed a wall that curves to meet the ceiling, mimicking the barrel-vault arches throughout. Where the wall intersects with the largest of the living room’s windows, they incorporated steel shelving around a Port Laurent marble fireplace. “It was a barrel-vault intersection,” Hagerty says, noting that he drew up more than a dozen plans before landing on this solution.

Finally, the architects concealed the exposed-concrete columns behind custom cabinetry in the kitchen and the newly created hallway, resulting in long, unobstructed sightlines. “It lets you focus on the beautiful space and the unobstructed views of the lake and city,” Toukoumidis says.

Once those problems were solved, the team turned to the material palette and furnishings. All the walls are painted in a specific shade of white with notes of black and brown that work equally well with warm or cool tones. It complements the custom European oak cabinetry and hardwood flooring, which have been cut into six-foot planks—twice as long as they would normally be—and laid in a herringbone pattern. “I was afraid that the smaller planks would look too busy,” Gearen says. “Good design responds to its environment.”

In the entry hall, the new curved wall covers previously exposed pipes and pays homage to the arched windows throughout.

Lighting was another key element. Over takeout one evening, the team tested more than a dozen lighting products for color and coverage, ultimately landing on an LED laser light that frames each of the arched windows, creating a soft glow that suits the sensuous curves.

In the same spirit, the ceilings in the kitchen and powder room have been held back from the wall, revealing a cove of indirect light. “We created layers of light to highlight the architecture and bring warmth to the space,” Toukoumidis says.

Johnson followed suit with her interior designs, selecting a simple bronze fixture to illuminate the dining area, which is furnished with a Bonaldo table and modernist chairs by Philippe Starck for Cassina.

It coordinates perfectly with the bronze pendants over the nearby kitchen island, which has an oak base and a waterfall-style porcelain faux-marble top—the same materials used in the master bathroom. “It’s important to have an easy flow, visually and physically, as you move through the space,” Johnson says. The pattern in the custom wool-and-silk rug that Johnson and Gearen designed for the living room, for example, plays off of the veining in the marble fireplace mantel and also references the waves on the lake. It’s an elegant backdrop for mohair-covered sofas and a pair of leather chairs Johnson bought for one of their first projects together.

As for the master suite, “It just needed to be calm and serene and let the architecture speak for itself,” interior designer Ruth Johnson says.

The sense of simplicity has been carried into the master suite, where Johnson found a spot for a buck suede-covered bed with built-in side tables that Gearen had long had his eye on. A pair of upholstered armless chairs in white completes the scene.

“The finishes and furnishings were carefully selected to balance the vaults, the curves and the views, which are the heroes of the space,” Johnson says.

The result lives up to Gearen’s lofty expectations and then some. In addition to hosting a score of guests, he has orchestrated a number of fundraisers there, easily welcoming as many as 150 people at a time. He credits the location atop the highest building in the neighborhood as a big draw.

“It’s fun because people want to see this place,” Gearen says. “It’s such a comfortable place to live, and I’m happy to be here.”