The 73-story Wilshire Grand Center is the first major skyscraper to be built in Los Angeles in a quarter century. (InterContinental Los Angeles Downtown)

Chris Martin, who heads Los Angeles architecture firm AC Martin, recalls that in 2007, he was paid a visit by Korean Air chairman and chief executive Yang Ho Cho. The two friends had bonded years before over their common interests. Martin, who in his spare time flew experimental aircraft, shared Cho’s interest in aviation, and as a University of Southern California alumnus and trustee, Cho had strong ties to the city where Martin’s firm had designed scores of local landmarks. But this time, Cho sought Martin’s help in solving a perplexing problem.

The subject was the Wilshire Grand, a 1950s-vintage hotel in downtown L.A.’s financial district. Years before, the Cho family’s sprawling conglomerate had purchased the structure for $168 million with the aim of reviving it from its faded luster. But the effort had stalled. Cho explained to Martin that it was a world-class location and that he wanted a world-class hotel to suit it.

“You can paint it,” Martin replied, “but the module is 1952. You can’t make the bathrooms bigger.”

Martin agreed to help figure out what to do with property, and eventually he reported back with seven different ideas. The last on the list was the most drastic: tear down the hotel and build a cutting-edge mixed-use hotel, office, and retail complex.

As Martin remembers it, Cho immediately responded, “That’s what I want to do.”

In the sky lobby on the 70th floor, the outriggers and buckling-restrained braces that protect the building against seismic forces are featured as dramatic interior design elements. (Wilshire Grand Center)

That glimmer of inspiration was the start of the first new skyscraper with office space built in downtown Los Angeles in 25 years. The Wilshire Grand Center, which officially opened in June, soars 73 stories, making it, at 1,099 feet (335 m), the tallest building west of Chicago. Thanks to an easing of antiquated fire safety requirements, it is the first tall structure built in downtown Los Angeles in decades without a flat roof, and the tower’s curvilinear silhouette and crown—designed to evoke the dramatic Half Dome rock formation in Yosemite National Park—have dramatically altered the city skyline.

But the $1.2 billion project—which includes 900 hotel rooms, 400,000 square feet (37,000 sq m) of office space, and another 45,100 square feet (4,200 sq m) of dining and retail space—would turn out to be a monumental challenge.

Economic uncertainties nearly stalled the project and compelled a major design overhaul. And creating a tower that was complex and elegant, yet environmentally sustainable and resilient enough to sit in an earthquake zone—necessitated architectural, engineering, and construction innovations, including a continuous concrete pour for the foundation that set what at the time was a world record. AC Martin, which not only designed the building but also managed the project, and construction contractor Turner also had to execute a just-in-time logistical process in which giant cranes hoisted materials—including 700 factory-built modular bathrooms—to the upper floors so that workers could install them the next day.

The result of those labors is a building that many in the Los Angeles real estate sector see as a transformative influence—one that will hasten downtown L.A.’s blossoming into the sort of mixed-use, round-the-clock core found in other cities of its stature across the globe. And the Wilshire Grand Center’s emergence seems to have triggered a surge of other downtown projects, emboldening developers and foreign investors to place their bets on the area as well.

A view looking up from an area in front of the “glass waterfall” skylight, overlooking the entrance. (Gary Leonard/Wilshire Grand)

Altering the Skyline

Initial plans called for the aging hotel to be replaced by a pair of towers—a hotel plus an office building—but by the time the entitlements were secured in 2010, Martin recalls, that concept no longer looked economically feasible. “The office market was flat,” he says. They considered building the hotel first and the office building next to it afterward, but after more than a year of additional discussions, the original concept was scrapped. “We came to the conclusion that it should be one building,” Martin says. The hotel would be stacked atop the office space.

Cho also asked Martin to manage the entire project to completion, an unusual role for a design firm. Martin says he turned down Cho twice before finally agreeing. At the time, Martin was still devastated by the loss of his son Patrick, also an architect at the firm, to cancer. “I said, I’ll take this on personally in his memory, without charge,” he recalls.

The decision to go with a single big tower sent Chris Martin’s cousin David Martin, who at the time was the firm’s lead designer, back to the drawing board. His grandfather, Albert C. Martin Jr., had collaborated on the design of Los Angeles City Hall, a 1928 architectural icon that was the last major high rise not to have a flat roof.

A city fire code enacted in the late 1950s required tall buildings to be flat-topped to accommodate helicopters for fire rescues, a rule that long limited the creativity of Los Angeles architects. But the Martins convinced officials to grant an exception because Wilshire Grand Center’s planned safety features, which include an additional stairway and a concrete-encased elevator shaft that could be used by firemen to get to upper floors, made it unnecessary. That led to the rule being scrapped altogether in 2014.

“When we were able to do that, we figured, if nothing else, this is a good legacy for the future,” David Martin recalls.

He says three ideas influenced the building’s design.

The first was that Wilshire Grand Center could connect to the new, walkable, transit-oriented downtown that was rapidly evolving and forge a link between the Financial District and the hip restaurant scene developing along Seventh Street. Rather than have the structure take up the whole site, he arranged for the public space—a large outdoor plaza at the intersection of Seventh and Figueroa streets—to connect to the nearby Metro Rail station.

Second, David Martin wanted the building to capitalize on the mild Los Angeles climate, both for ambience and energy efficiency. As a result, the Wilshire Grand Center has “as many openable windows as possible in the hotel,” he says. “The ballroom has a big window and a garden.” In addition, the 17 floors of office space at the base of the tower each have individual fan rooms to provide more direct access to outside air.

The third idea was to create an iconic shape that emphasized verticality, “an old idea, going back to the pyramids and gothic cathedrals—to connect to the sky,” he says. Other influences slipped in, such as the sweep of airplane wings and Half Dome. “My cousin and I and the Cho family have all been to Yosemite, so that was one of the things that was easy to talk about, the natural reference,” David Martin says.

“It was interesting that we ended up with a building that started to have parabolic shapes,” he says. The design grew so complex that modeling it was beyond his computer skills. Fortunately, he says, “we had these brilliant young kids from Harvard who knew how to parametrically model. . . . We learned from the skills that they brought to the table.”

The Wilshire Grand Center’s entrance, as seen from Figueroa Street, features an elaborate, sloping skylight that has been described as resembling a waterfall. (Wilshire Grand Center)

Design, Project Management, and Construction

Building a tall building with an exotic shape was all the more challenging because of the location. Downtown L.A. is only 30 miles (48 km) west of the massive San Andreas Fault, and other smaller faults run through downtown. Engineering firms Brandow & Johnston and Thornton Tomasetti worked together to provide solutions that make the building, in the words of technology publication Wired, “one of the most advanced in the world when it comes to seismic engineering.”

For stability, the tower rests on an 18-foot-thick (5.5 m) mat foundation that weighs more than 82 million pounds (37 million kg). “We couldn’t drive piles deep enough, so we needed a monolithic core the size of a football field,” says Chris Martin.

To create such a base, Turner Construction set what at the time was a world record for the longest continuous placement of structural concrete, with more than 200 trucks moving in choreographed fashion to put in place 21,200 cubic yards (16,209 cu m) of concrete in 18-and-a-half hours, according to the construction company’s website.

“Each truck driver had a phone app telling him where to be,” Chris Martin says. “They had 45 minutes to deliver. It came off without a hitch.”

Making the upper structure resilient required some ingenuity. Leonard Joseph, a principal at Thornton Tomasetti, explains that because the building would have a slender core, the concept of using outriggers to reach out from it to engage perimeter columns was a key part of all the potential schemes. But using conventional steel members—wide-flange I-beam or box shapes—on the outriggers was problematic.

An outdoor cocktail lounge provides a 360-degree view of downtown. (Gary Leonard/Wilshire Grand)

“In some parts of the world subject to high winds and more moderate seismic forces, it’s possible to size the outrigger members and connections for hurricane or typhoon forces, and then check that they can also resist seismic forces,” Joseph wrote in an email. “In L.A., it’s the reverse. Conventional members sized for wind would be overloaded in a major earthquake.

“But the ‘brute force’ alternative—upsizing outrigger members and connections—would result in very large earthquake forces acting on engaged walls and columns, requiring them to be even stronger. In particular, where the outriggers connect to the central concrete core walls, brute-force horizontal thrusts from outriggers could become large enough to damage the walls.”

To avoid such problems, Joseph explains, the engineering team came up with the solution of using buckling restrained braces (BRBs)—essentially, long steel bars coated in a bond-breaking material and encased in steel boxes or tubes filled with grout. When the building moves, the steel bars compress or stretch as if they were taffy. Kinetic movement is converted into heat, which in turn is absorbed by the braces.

“BRBs aren’t a new technology,” says Tammy Jow, AC Martin project director and senior designer. “But doing BRBs at this scale in a tall building in downtown L.A. is new territory.”

The engineers also sought some changes in the tower’s signature top.

“The original concept was a series of light, lacy legs supporting the sail glazing,” says Joseph. “Thin members laced together with crisscrossed steel bars are commonly seen in historic structures, such as early truss bridges and the Eiffel Tower. However, these types of members do not perform well under the severe seismic conditions at the top of this tower, since local buckling of a thin member can lead to overall failure. If the members were to be upsized enough to avoid such buckling, they would no longer be ‘lacy’ enough to meet the architect’s concept.

“So the architect agreed that a more straightforward braced-frame approach—a grid of beams and columns kept square by diagonal and X braces—made better sense.”

Simply erecting a building that was so large and complex in congested downtown Los Angeles was another daunting challenge.

“It became apparent that time was more expensive than concrete, steel, and glass,” Chris Martin says. The project employed 1,500 construction workers in three shifts, and keeping them continually busy was crucial to keeping the project affordable. “If it takes an hour to get your drywaller to the 57th floor to hang drywall, he’d better not have to go back down to his truck.”

To optimize efficiency, massive cranes worked all night to load material on the floors where it would be needed the next day, a logistical process that Chris Martin describes as “a vertical assembly line.”

In some instances the builders relied on modular parts. After an analysis showed that building bathrooms was particularly time consuming—“we’re talking potentially 2,000 man-trips in and out to put in tiles, fixtures, the ceiling, and so on,” Chris Martin notes—AC Martin opted to have hundreds of complete bathrooms built at a factory in Madera, California. They were trucked nearly 300 miles (488 km) to downtown Los Angeles, where they were hoisted by cranes and anchored in place so that workers only had to hook up the plumbing the next day.

One of the Wilshire Grand Center’s most striking elements—a massive skylight that slopes dramatically, elevated over the entrance to the hotel and office space—required even more ingenuity. Because curved glass panels were prohibitively expensive, the skylight was built with essentially flat panels subjected to a process called cold-bending, in which glass is slightly contorted and then inserted into frames to maintain that shape. AC Martin’s designers used software to adjust the forms and massage them enough so that the skylight could be built.

“People walk by it, and call it the ski jump or the waterfall,” Jow says. “It’s pretty interesting. It stimulates people’s imaginations.”

The Wilshire Grand Center also has LED lighting integrated into its skin. “We’ve got a 60-hertz refresh rate, with any color we want,” Chris Martin says. “We have the capacity to do high-speed, moving color lights, with good definition.” At the building’s grand opening in June, onlookers could gaze upon a pulsating light show that displayed some of the building’s capabilities.

But, in addition to the attention-getting technology, the Wilshire Grand Center incorporates numerous features designed to make it sustainable. The building is designed to collect rainfall in a cistern in the basement, then pump it back up to cooling towers on the 11th floor.

Transformative Effect on Downtown

The Wilshire Grand Center marks the latest stage in the long, gradual evolution of downtown Los Angeles that began in the late 1990s with the opening of Staples Center and the passage of the city’s adaptive use ordinance, real estate broker and consultant Hal Bastian says. That ordinance allowed the conversion of historic buildings and office space to provide the residential units needed in order to accommodate a sizable downtown population.

“It’s not so much a catalyst as a supercharger,” he says. “It’s keeping us in motion toward what cities are supposed to be doing in their downtowns—a dense built environment where people use public transit instead of relying on cars. The kind of confidence that this building brings to the real estate market here is quite incredible. Now we have an iconic building in downtown, with an outdoor bar on the 73rd floor. It’s teaching us how to live in a high-rise environment.”

Michael Soto, a research manager at real estate firm Transwestern, also sees Wilshire Grand Center as accelerating downtown L.A.’s metamorphosis and attracting a more diverse mix of business tenants—tech companies, advertising agencies, architecture firms, and the like—who once might have headed straight to the city’s Westside. “There was a need for a brand new trophy skyscraper with all of the amenities that growing tenants want,” he says.

Bill Allen, chief executive of the Los Angeles County Economic Development Corporation, sees the new building as a powerful magnet for foreign investors who in the past might have shied away from downtown, in part because of the regulatory gantlet that projects once faced.

Allen credits Cho at the onset with having the wisdom to cultivate a good working relationship with then mayor Antonio Villaraigosa and his staff, as well as the city council. The mayor, in turn, established a cross-disciplinary team in the city’s Planning Department and Building and Safety Department, whose members worked together to help expedite the permitting process. Those officials, according to Allen, established parallel processes for permitting and approvals that helped advance the project swiftly. “If things had to happen sequentially, it could take a long time to build a building like this,” he says.

That culture of cooperation, which has continued under Mayor Eric Garcetti, has encouraged other developers to see downtown as a place where they can complete projects quickly enough to generate a handsome return, Allen says. He cites as an example Chinese developer Greenland USA’s $1 billion Metropolis hotel, condominium, and shopping complex just a half mile (0.8 km) from the Wilshire Grand Center. The Metropolis is slated for completion in 2019. Another Chinese developer, Oceanwide Holdings, is erecting the $1 billion Oceanwide Plaza mixed-use complex across from Staples Center.

“There’s now more development activity in downtown that at any time since the 1920s,” Allen says.

Chris Martin sees the Wilshire Grand Center as having created important momentum. “It serves as the poster child for Los Angeles to the rest of the world,” he says. “If you want to make a significant investment, you can make it in Los Angeles. It’s helped prime the pump.”

Patrick J. Kiger is a Washington, D.C.–area journalist, blogger, and author.