To walk the streets of South Lake Union (SLU) is to be bathed in the thrilling glimmer of new construction and the hum of global biotech and software engines, interspersed with echoes of its maritime past.

But does the neighborhood have a soul?

It’s a question that stems, in part, from grumbling members of Seattle’s old guard, suspicious of SLU’s luxury buildings and millennial office workers, and mourning the loss of historic buildings and affordable housing. But the area’s fast-paced growth and radical change raise questions that reach beyond a klatch of chattering naysayers, especially as Vulcan Inc., the dominant force behind SLU’s boom has been selected to redevelop Yesler Terrace in January.

At first glance, South Lake Union has all the elements that make a great neighborhood: safety, density, residential/work opportunities, transit and amenities—including a Whole Foods supermarket, hip restaurants and coffee shops. But do these ingredients add up to the immaterial essence that stirs devotion and engagement?

“South Lake Union has a lot of services and lots of people walking around, but I’m not sure it has that neighborhood feel yet,” says Curt Archambault, a management consultant who has lived in the neighborhood with his wife since 2007. But Archambault says that, compared to Capitol Hill and Pioneer Square, South Lake Union is still evolving. “This neighborhood is in the teenager stage,” he says. “And like a teenager, it’s trying to find its identity.”

“Yes, it may be wonderfully developed with plazas and parks, but how do you tell you’re not in Houston?”

To others, SLU has a perfectly mature soul already, one that dates back to the 19th century’s scrappy maritime and timber industries, and the immigrant shanties that sprang up to support them. “What gives South Lake Union soul is the combination of innovation and history that have flowed through it for decades and transformed it from one type of neighborhood to another,” says Lori Mason Curran, real estate investment strategy director at Vulcan Inc. To date, Vulcan has developed 4.6 million square feet in 22 new office, biotech, residential and mixed-use projects in South Lake Union.

Transformation is a constant in South Lake Union, a shape-shifting that also comes with long-standing tension between attachment to the past and ambitious visions of urban planning. Progress is unstoppable, but it’s the size of the steps and what gets crushed underfoot that worry some observers.

“What contributes to soul is not essentially what’s new. It’s remembering the past and the stories told in those remnants and vestiges,” says Peter Steinbrueck, an architect/activist, former Seattle City Council member and now a candidate for mayor. “There’s something to be said for honoring what already exists there.”

At this point, nine to 14 sites have been designated landmarks in SLU, depending on where you draw the boundaries, including the Kelly-Goodwin Building (now home to Tom Douglas Inc., at 320 Terry Ave. N), the Naval Reserve Armory (home to the Museum of History & Industry, or MOHAI) and the Van Vorst Building (415 Boren Ave. N). But preservationists say the potential exists for designating many other landmarks and preserving the spirit that comes with age and authenticity. “Yes, it may be wonderfully developed with plazas and parks, but how do you tell you’re not in Houston?” says Chris Moore, field director of the Washington Trust for Historic Preservation. “There’s a reason why people like living in historic lofts and pay top dollar to live in a church that’s been converted.”

Vulcan touts its commitment to preservation, citing the careful removal and storage of the auto-showroom facades from a designated landmark before widening Mercer Street. The facades will be incorporated into the design of the Allen Institute for Brain Science. “Our goal has been to give a nod to the history of SLU in terms of preserving historic structures, but also to making sure it creates an economic engine for the city,” Vulcan’s Curran says.

Of course, buildings alone don’t put soul into an urban landscape. That requires people. While the city continues to flex its development muscle, most recently with a rezoning proposal that would allow buildings as high as 400 feet in SLU, some fear the focus on density may undermine the goal of greater vibrancy. For SLU to make a strong neighborhood a part of its current incarnation, community advocates and preservationists say, the city and the area’s developers would do well to include more public places and activities. “If it’s only corporate complexes housed in big towers, you’re not going to be a great urban center,” Moore says.

While some sneer that there’s still nothing much to do in South Lake Union except drink coffee and have dinner, a cultural calendar of sorts has begun to emerge. The Seattle International Dance Festival held public performances in SLU last year, and creative installations and exhibits dotted the streets last September as part of the Seattle Design Festival. The annual Lake Union Wooden Boat Festival and the South Lake Union Block Party remain popular summer activities.

One of the intriguing installations during last year’s design festival was performing artist C. Davida Ingram’s cell-phone tour, called “Detour: Cascade to South Lake Union,” celebrating the Cascade neighborhood, a funky, diverse micro ’hood she fears will be subsumed by the SLU boom. The type of activities and businesses developing so far may be creating what Ingram calls a “monoculture” of residents that excludes families, ethnic and racial diversity, and the less affluent. “SLU is becoming a consumer lifestyle district,” she says, “which is not the same thing as a neighborhood.”

At Veer Lofts, at Ninth Avenue N and Harrison Street, some residents in the 99-unit building are creating soul themselves through a tight-knit community that socializes together, especially when the destination is nearby. Wendy Simons is one of those residents. Simons moved to SLU from Bellevue, never to look back on her former suburban lifestyle, where making personal connections had been a challenge. “I’m a people person, and in Bellevue, whenever I threw seeds, they didn’t grow,” she says. “Every time I throw seeds here, they spring right up!”

Simons, who is originally from Cape Town, South Africa, feels right at home. “I’ve lived in America for 40 years, and this is the most at home I’ve ever felt.”

But some efforts to increase the stickiness of the SLU community events, such as the Cascade Farmers’ Market and a monthly art walk, have lost steam and petered out. And untapped treasures such as Denny Park, the city’s first public park, offer visitors mostly solitude, even on the sunniest days. “There’s more we can do in that park to get people out of their workplace and mingling in communal areas,” says SLU resident Archambault. “In San Francisco, parks fill up with people on nice days. You don’t see that here.”

The focus, though, tends to be on the new—the refurbished Lake Union Park, the relocated MOHAI and the expanding Amazon footprint—to create the right mix that will enliven the neighborhood.

Some establishments aren’t designed for all comers. The so-called Amazon cafés—Caffé Vitta in the Van Vorst Building and Victrola Espresso Bar on Boren Avenue N—require Amazon employee IDs to get in. The restriction highlights the gray area between the public and the private in SLU. The public is welcome at Buster Simpson’s Ping Pong Plaza, outside 401 Terry Ave., but the site doesn’t have the same accessible feeling as the outdoor chess game in Westlake Park. Vulcan plans to purchase an alley from the city at Mercer and Ninth Ave. N and transform it into a landscaped public plaza. But it remains to be seen if open spaces in private hands attract the diverse multitudes necessary for a truly vibrant community, or create an isolation that risks turning SLU into a company town.