When San Francisco architect Cass Calder Smith decided to expand his practice in the mid-2000s, he needed to establish a New York base where he could both live and work. The move was a return to the bicoastal lifestyle of his childhood—a son of separated parents, he split his time between his mother, who lived on a commune in Northern California, and his father in New York, a writer for the Village Voice. After looking at lofts in the Flatiron district and deciding they were too big and expensive for his bachelor self, he stumbled upon a modern building in the then no-man’s-land area of Manhattan south of the West Village and north of Tribeca. Calder Smith bought the smallest one-bedroom on a top floor of the building, with views of practically every inch of SoHo in all its water tower–topped glory.

For a while, the space was the ideal pied-à-terre, but then his business grew. After a couple of years, Calder Smith was spending more time in New York than in San Francisco. It was time for more space. On a whim, before hitting the open-house circuit, he decided to walk down the hallway and knock on his neighbor’s door with an offer for his one-bedroom place. The neighbor almost immediately said yes (it was the height of the real estate boom in New York). “I bought it, but for probably more than I should have,” Calder Smith admits.

Still, the offer meant he could keep and expand his modern high-rise apartment, located in the quiet, slightly off-the-map, almost-secret neighborhood just blocks away from where he had grown up in the West Village. No need to give up the short walks to Hudson River Park that he loved or the views, which became the focal point of the gut renovation and merger of the two apartments. “Five large windows along one wall allowed me to situate the bedrooms in the far corners of the apartment and have one large space in which to relax, entertain, and work,” says Calder Smith. Pocket doors to the bedrooms also mean that, when they are tucked away, all five windows allow wider views. “It was really perfect for me,” he says.

Visitors naturally gravitate toward the view, so Calder Smith made sure that each window has built-in seating. “Like so many condos, that’s where the heating is located,” Calder Smith explains. “The units were originally covered with metal, which just looked bad. The bottoms of the windows were around seating height, so I made them into benches.”

But an apartment can’t be defined by what’s outside its windows. “I’ve worked on a lot of condominiums that have similarly huge views. It’s easy to concentrate on them, but if you don’t design something as a counterpoint, you really end up with a space that feels kind of one-dimensional and mono. You need something more stereo.”

Therefore Calder Smith placed “the monolith” directly opposite the windows: It’s a kind of multi-purpose room divider, painted in the architect’s signature dark blue, that hides some mechanicals and is both a bookshelf and storage space. Its placement fractures the openness of the apartment’s main area, creating a hallway where Calder Smith displays his art in a light-controlled setting. The monolith also obscures the entrances to the bathroom and laundry. On the other side, Calder Smith created a seating area around a 1970s chrome-and-glass coffee table scored online and placed a David Weeks sofa within arm’s reach of the architect’s many tomes. “When guests are sitting there, they’re not looking at doors,” Calder Smith says. “They’re looking at a library.”

Though only 1,600 square feet, the apartment’s main space feels vast and loftlike, thanks to the minimalist cooking space. “Traditional kitchens aren’t really proportioned to be featured,” Calder Smith says, “and upper cabinets are usually clunky, so why show them off? That’s why everything in the kitchen is white and as simple as it can be.” The architect selected sleek Bulthaup cabinetry, complemented by a large stainless steel island that anchors the space. “I wanted it to be a kind of people magnet.”

Speaking of areas that root people in place, there’s no formal dining room. Instead, Calder Smith uses Eames chairs and a large Saarinen Tulip table with a black base. “I needed something that could float without relating to a defined space—the ellipse shape allowed this. I typically keep it near the windows as a place to spread out work, but for a dinner, I move it away from the windows and put chairs around it.” During a party, of which Calder Smith has had more than a few, the eight-seater is substantial enough to hold everyone’s drinks and several towers of fresh seafood and handle kids playing underneath it and even the odd bump or two.

It’s easy to forget that what made this apartment possible was an unprompted knock on a neighbor’s door. Next came the decision to bookend the space with what are essentially two master bedrooms, resulting in a large and flexible enough space to accomplish any number of environments for living or working. But luckily, for Calder Smith, it functions best for entertaining, and that suits him just fine. “My real office is just four blocks away.”