On a bright August morning, Bob Clark, the founder of construction giant Clayco, stops by the new $850 million, 19-acre Obama Presidential Center, which he helped build, in Jackson Park on the South Side of Chicago.

After a quick checkup on the “Obamalisk,” as he fondly calls the complex’s central eight-story spire of granite, glass and concrete, he gives a speedy hello to former White House senior advisor Valerie Jarrett, who is now CEO of the Obama Foundation. Then he’s off, hopping in the back of a white Escalade and speeding down Lake Shore Drive to another of his projects, which could arguably be of even greater importance to Chicago and the world.

Situated on a 440-acre Lake Michigan site that used to be a U.S. Steel factory, “Quantum Shore” will be one of the lar­gest quantum computing campuses in the country when it opens at the end of 2027. Tenants include IBM and Palo Alto, Cali­fornia–based PsiQuantum, which plans to build a million-qubit quantum computer here. Such a machine would be unimaginably powerful, able to crack the usual types of encryption that keep most of the world’s computers (and bank accounts) secure. It could even someday speed up AI learning by dramatically reducing training time for certain complex deep-learning architectures.

Quantum Shore is a challenging—and expensive—place to build. The first 128-acre phase is being developed by Clark’s real estate development subsidiary CRG and the Midwest office of real estate giant Related Companies. It will cost some $12 billion, $500 million of which is being ponied up by the state of Illinois. Because quantum bits, or “qubits,” are extremely sensitive to environmental conditions, the structure will feature a cryogenic plant that will feed supercooled liquid helium and nitrogen to the computers. “The only way they can stabilize the chip is by being cooler than outer space,” Clark says as 550-ton cranes rumble past. Marveling at the complexity of the project, he recalls when PsiQuantum’s CEO told him he was going to design a building that would “change everything.”

It’s fitting that Clark, 67, is leading work on this next-gen project. He has been building data centers since the 1980s and completed 16 of them last year. He has another 77 in the works across 13 states. Data center construction is expected to account for 75% of Clayco’s nearly $12 billion in 2026 revenue, helping boost revenue by 43% over 2025. “I’ve been in the data center business for most of my career, but never would’ve imagined what’s happening today,” he says.

When Clark got his start four decades ago, a data center was simply a couple of computer rooms added to the back of a bank. Now Clayco, which is based in Chicago, is erec­ting what amount to self-contained (and mostly human- free) billion-dollar cities housing 100,000 or more of the world’s most advanced GPUs for clients including Amazon, Microsoft and Oracle. To do it efficiently, at scale, Clayco owns and operates its own architecture, concrete, procurement and logistics companies. It’s a machine optimized to feed AI’s insatiable machines.

U.S. spending on data center construction has more than tripled since 2023 to an expected $75 billion this year, per Census Bureau data. And that’s excluding the cost of buying the actual computers, which can amount to 40% of the total project cost. Jeff Blau—CEO of Related and Clark’s partner on Quantum Shore, as well as a $1.2 billion center for CoreWeave in Cheyenne, Wyoming—says data center demand plus high interest rates have crowded out many other big construction projects. “This is unprecedented. We’ve never had something with such strong demand and such scale at the same time,” says Blau, whose Related Digital has $55 billion worth of data center development underway. That’s good for the construction companies.

Close to 1,300 data centers are already up and running across the country. These concrete-and-steel beehives guzzle around 70 million gallons of water each day and require a constant 62 gigawatts of power to function. That is an insane amount of electricity. New York City, by comparison, draws six gigawatts on average. Another 2,142 centers are planned or in the works, according to infrastructure intelligence firm Cleanview.

One byproduct of the AI boom is how wealthy it has made Clark. His net worth has quadrupled in the past three years to $7 billion, enough for him to debut on The Forbes 400 this year at No. 245. Another byproduct: sur­ging opposition. A recent survey by the Annenberg Public Policy Center found that 61% of Americans oppose building data centers in their communities, up from 49% just four months ago. According to Data Center Watch, $18 billion worth of projects have been blocked, and an additional $46 billion of construction has been delayed.

Clark is unfazed by the anger. He likes to stay focused on results. “We don’t see any warning signs on the horizon,” he says, pointing out that this is not like the 2000 dot-com bubble, inflated on hot air and hype. Today’s hyperscalers are the best-capitalized companies in the world. “I’m not worried about them paying my bill.”

C lark’s love of building began in the fourth grade, when Ozark Airlines was erecting a new headquarters next to his St. Louis elementary school. Afflicted with “attention defi­cit,” as he calls it, Clark was obsessed with watching the construction through the classroom window. His father, who turned a seventh-grade education and a lot of “intuitive capability” into his own painting company, encouraged young Bob’s interest by asking for daily updates.

Clark soon moved on to moneymaking ventures like washing cars, sealing driveways and driving a snowplow. The fact that he lost his right eye at age 13 to a pellet gun accident never slowed him down. It helped that he could multi­task, but staying on a single task was a challenge. He dropped out of college (he won’t say which one) just five weeks after enrolling and used $63,000 of the insurance money from losing his eye (about $300,000 in today’s dollars) to buy 37% of a small St. Louis–based outfit called Machine Maintenance & Equipment. He spent a few years selling Ingersoll-Rand drilling rigs to wildcatters in Oklahoma and Arkansas; in 1983, when he was 23, he sold his stake to his partners for about $1 million ($3 million, adjusted for inflation).

He used the proceeds to start Clayco, which for the first 29 years of its existence was headquartered in St. Louis. His first big break came after a small job doing interior buil­ding work for the Mercantile Bank in downtown St. Louis. Its CEO, Donald Lasater , liked him enough to tap the then-27-year-old to build 15 branch banks with drive-throughs. He got his first “primi­tive” data center job (with raised access floors and lots of cabling to connect banks of bulky computers) after doing interior finishing work for the Farm Credit Banks of St. Louis in 1986. “I was in the right place at the right time. They should not have given that job to me.” That led to a data center for Citigroup, followed by a string of contracts for offices, stadiums and hospitals.

Right after he started Clayco, Clark and his wife, Ellen, took in one of his “workers,” a 12-year-old boy named Todd Weaver who showed up at a construction site asking for a part-time job. Initially, Clark paid Weaver to pick up trash and pull weeds. Weaver’s mom had cancer and diabetes and couldn’t support her son. After a couple years, Clark arranged for him to move in with him and Ellen and their young biological children, one of whom now runs CRG. Today, Weaver has his own has his own firm that also builds data centers and he has even partnered with his mentor, who loaned him $150,000 in 2002 to start his business. “He was worse than a friggin’ bank,” says Weaver, now 55, laughing as he recalls how Clark would ask him for business updates every Sunday dinner. “I paid him back all his money in six months.”

By the turn of the millennium, Clark had a steady stream of jobs building corporate headquarters. He even erected the new Busch Stadium, home of the St. Louis Cardinals, which opened in 2006. His biggest customer at the time, Proc­ter & Gamble, warned him in 2007 about a pullback in capi­tal investment and the potential economic consequen­ces. “It was the best advice I maybe ever got in business,” says Clark, who quickly restructured $700 million of personally guaranteed debt with two dozen banks. He also tightened the belt at work, cutting pay by 20% across the board and eliminating bonuses and 401(k) matching for a time. By the time Lehman Brothers collapsed in September 2008, “we were already turning the corner.” Staff stuck with him despite the temporary cuts. Today, Clayco’s top executives own 40% of the company, a stake worth an estimated $4.4 billion.

Behind the scenes he had a much bigger problem. In 2005, Ellen was diagnosed with cerebroretinal vasculo­pathy, which causes the deterioration of small blood vessels and leads to strokes. The Clarks were in the Oval Office in 2009 when President Obama signed an executive order ending the federal ban on embryonic stem cell research, which might help find a cure before the congenital disease possibly affects their children. (To date there is still no cure.)

When Ellen died at age 50 in 2010, Clark, distraught, trekked around Asia, including Japan and India, where he visited Varanasi , on the banks of the Ganges, one of India’s spiritual capitals. He came back renewed, reclaiming his self-described superpower of “always knowing I’m the happiest person in the room” and determined to grow his business bigger than ever. He relocated Clayco’s headquarters to downtown Chicago, and in 2015 married a dentist. Presi­dent Obama tapped him to help scout sites, select architects and supervise work on what would become his presidential library. “Whenever the Obamas had an issue with construction, they would call Bob,” says Penny Pritzker, the former commerce secretary and billionaire Hyatt Hotels heiress. “He would make sure it got done right.”

Chicago connections and the Obama seal of approval helped Clayco land big projects like the new terminal at O’Hare Airport (started in 2019), the Lurie Children’s Hospital just outside the city (planning underway) and of course Quantum Shore, which got another boost when it was designated as a qualified opportunity zone. Under the Tax Cuts and Jobs Act of 2017, investors in the quantum project can roll existing capital gains into the new project at a stepped-up basis and pay no taxes on new capital gains if investments are held for ten years. “You’ve got states competing with states,” Clark says. “So to be in the game you have to really know how to use all the arrows in the quiver.”

C lark build his first hyperscale center, for Microsoft, in 2016. “What we didn’t know then is we weren’t even in the first inning,” he says. A decade ago, a big data center in the U.S. was 50 megawatts, and the industry used 5.5 billion gallons of water. The new centers use far less water today to do the same amount of computation, but there are many more of them. By 2028, hyperscale data center water consumption will likely climb beyond 16 billion gallons a year, per a Lawrence Berkeley Lab report.

Among Clayco’s biggest jobs is Amazon Web Services’ $13 billion, 2.2-gigawatt Project Rainier near South Bend, Indiana. Clayco and four other contractors are responsible for clearing, grading and paving the site, installing the concrete slabs and putting in the electric and water systems, plus the tubes that house the delicate fiber optic cables.

Clark keeps improving his methods, moving toward a prefab approach with modularized construction. That both cuts costs and speeds things up, vitally important amid the fast-paced AI wars. “You can’t solve exponential demand with linear construction methods,” he says. Rather than build out miles of complex electric and cooling systems onsite, Clayco and its subcontractors are now making components in controlled factory settings using in-house design and engineering teams. That reduces the number of electricians and other skilled workers needed on job sites. It’s a huge help, Clark says, acknowledging that one of his biggest challenges is retaining an army of 50,000 full- and part-time workers, including 13,000 electricians (plus subcontractors) on 100 projects nationwide.

Clayco incorporated this approach for finance billionaire Michael Novogratz at Galaxy Digital’s recently completed Helios data center , which was converted from a former West Texas crypto mining site. To build it, Clark trucked in 120 premade electrical houses (to control and distribute power), 95 chiller skids (heavy-duty air conditioning systems) and ten pipe racks holding conduits for fiber optics, water and electrical lines to the site in remote, rattlesnake-infested Afton, Texas. “That’s not a project you would build next to a neighborhood,” he admits. No kidding.

New York and Texas have issued data center moratoriums; Pennsylvania now has strict regulations. And despite his “what, me worry?” attitude, Clark is feeling the heat.

Many agree. New York and Texas have issued a moratorium on new centers, while Pennsylvania now has strict regu­lations. Even Loudoun County in northern Virginia, home to more than 50% of the data centers in the state with more than any other, has paused new development . And despite his “what, me worry?” attitude, Clark is feeling the heat. In St. Charles, Missouri, CRG withdrew plans for a $1 billion, 1.5 million–square-foot center after resi­dents condemned attempts to quietly push it through local government.

Regulatory delays over air, water, and pipeline permits have meanwhile slowed progress on Clayco’s work on its biggest center yet, the $50 billion, 2.45-gigawatt Project Jupiter, for Oracle, in Doña Ana County, New Mexico. “Project Jupiter is exactly the kind of opportunity we should be pursuing,” says Clark. “It represents a significant investment, good jobs, and the kind of infrastructure that positions a region to compete for decades.” And yet Oracle in late September spooked markets by issuing a force majeure notice to Jupiter’s financial backer Blue Owl, saying that if delays pushed completion beyond 2028, it would hold off paying rent. Nervous investors traded down the price of $18 billion of bank loans tied to the project to 89 cents on the dollar.

“Big projects are complicated. This is normal everyday stuff, just more public, so you see how the sausage gets made,” says Clark when asked about Project Jupiter. Besides, he argues, the stakes are too high for failure to be an option: “This infrastructure is too critical to America’s future and to national security. It’s going to get through whatever painful process.”

Perhaps not quite as critical is a $6 billion data center Clayco is trying to buid on spec. Less than an hour away in Festus, Missouri, it landed approval in 2025 but has since faced intense opposition. “We feel like we’ve been duped from the beginning,” says Lori Merriman, who lives 1,500 feet from the site that’s now crossed by high-voltage power lines; she has raised $60,000 to fight back.

Clark says the town of 14,000 will benefit greatly from the center, which will add jobs and contribute an estimated $1.3 billion in tax revenue and public benefit payments over 25 years. “It’s going to be a game changer for their schools, their roads, their fire department,” he adds, noting that he expects to start work in early 2027 on an updated design that is meant to be quieter, use less water and sit farther from nearby homes. “We’re going to use AI to make you smarter, more productive and grow faster,” he adds, describing those who are calling for moratoriums as showing a “terrible lack of courage.”

With spending on data centers likely to reach $15 trillion in the U.S. by 2050 (per PwC), slowing the AI revolution is likely a quixotic task. For every project that’s paused or canceled, others welcome the business with open arms, especially in remote, struggling areas. While nearly nine of ten existing data centers are in urban centers, two-thirds of those being planned are set to rise in rural areas, according to the Pew Research Center. “There are so many projects proposed and so much underlying demand that even if community opposition stops or delays some,” Clark says, “there are still more viable projects than the industry has the capacity to build for the foreseeable future.” In fact, he says he gets calls every week from developers who have land but can’t find a builder.

Still, he’s hedging his bets, careful not to ignore clients that predate the data center surge, such as the $6.5 billion worth of truck factories he’s working on for electric vehicle maker Rivian in Illinois and Georgia . “He’s very hands-on. He knows the details and really cares about the partners,” says Rivian’s CEO, RJ Scaringe.

“Builders are always a couple projects away from going out of business,” Clark says, only half joking. Besides, if the data center boom does go bust, he could finally work on his legacy, which he hopes will be designing more creative affordable housing, not structures for compu­ters. As his late wife, Ellen, told him years ago, it would be a disaster if his only legacy was the buildings themselves when what happens inside is a thousand times more important.