Too often, backyards take a backseat to the immediacy of interior renovations, and, after the fact, connecting the spirits of the two is a challenge. For Jen Chaiken and Sam Hamilton, the imminent arrival of their twin daughters signaled that it was time to tackle the “hillside of weeds” behind their San Francisco home. The project required negotiating not just an exigent landscape, but also a litany of complicated municipal codes based on the bordering city street.

In spite—or perhaps because—of the restrictions, Chaiken and Hamilton were determined to approach the project on their own terms. “We wanted to enjoy the process,” Chaiken says. The couple chose nearby San Anselmo landscape architect Eric Blasen and his business partner and wife, Silvina, for the venture. Blasen’s interpretation of imaginative play aligned with the couple’s desire to create a space that catered to both the whims of children and aesthetics of adults—a yard that would be more Tadao Ando than Magic Kingdom. Inspired by the Japanese architect’s approach to concrete, Blasen decided that the same minimalist aesthetic could translate well in a play space.

More than anything, however, “the site drove the design,” Blasen explains. “The big ‘aha!’ moment was when we decided to create usable space out of the slope,” he says. They honed in on a gently terraced scheme in which each of four levels offered a different platform for play with one additional condition: The area must also be a beauty to behold from above. The three-story house has both a balcony and roof deck—the adult playground—from which an unbroken vista of the entire city can be seen. Looking down to a pleasing view was as important as looking up and seeing the skyline.

Before construction could begin, however, preparations had to be made to ensure that the new space wouldn’t put any pressure on the city-owned fence abutting the yard. Nine load-bearing steel piers were drilled 20 feet down to provide the skeleton for a new 44-foot-long wall along the southern edge of the garden—18 inches in from the existing partition—to meet municipal building requirements.

Once these structural accommodations were made, the design began to take shape. The flat upper terrace, which hosts a cantilevered concrete bench and is primarily where the parents sit and watch activities unfold, leads into a steep slope with three side-by-side elements: steps, a sloped lawn, and a concrete slide. “Everyone gravitates toward the slide,” Chaiken says of the feature, which harks back to a less-litigious time when public cement slides were more common. Accent details, like the flat handrail and stone stairs, mirror those repeated both inside the home and out front, respectively; Blasen worked directly with architect Tim Gemmill to ensure a cohesive feel between the spaces.

A small sandbox and herb garden—valuable real estate for fresh additions to daily meals—share the lower level. Beneath that is a small area that the couple anticipated would be an ideal place for Hero, the family dog, to do his business, though, as it turns out, he’s not particularly fond of that spot; instead, the mulchy, fenced-in space serves as the entryway to the small shed where garden gear and warm-weather toys are stored away in winter.

It took a few years for the twins—now six years old—to begin enjoying the yard. But today, it’s a favorite spot on sunny days at home, and even when the cloud cover hangs low, the space manages to retain heat within its sturdy walls. Plus, between its promise of play or quiet time, it nearly always provides an answer to the age-old kid conundrum: “Mom, I’m bored. What should I do today?”