Marc Andreessen made his fortune founding Netscape and investing millions into speculative startups, but his father-in-law is the man who made "Silicon Valley" possible. And ugly.

Before tech began pouring out of Stanford University, Santa Clara Valley was thriving as one of the most bountiful farmlands on the planet. But where people saw flowering orchards, John Arrillaga envisioned miles of grotesque office parks lining 101. And 50 years ago, he began pivoting the valley to match his vision.

In a profile of Arrillaga, Fortune takes a look at how he turned himself into a Bay Area technology land baron:

He and business partner Richard Peery are the real estate developers who had the foresight in the 1960s to buy up the Valley's fruit orchards and turn the farmland into thousands of acres of low-slung office parks and campuses that have come to house Intel, HP, Apple, Google, and more. All told, the duo have erected more than 12 million square feet of office space and sold or leased tens of billions of dollars in property–an effort that has made Arrillaga, worth more than $2.5 billion, perhaps the richest man in Silicon Valley who didn't make his money by starting a tech company.

Fortune spends most of its article cheerleading Arrillaga's real estate empire as some sort of benevolent godfather of the Valley. But even Fortune struggles to be enthusiastic over the aesthetics of his developments, beyond their ability to sprout fortunes:

For all of Arrillaga's involvement in the minutiae of bathroom tile and landscaping, his projects are not quite things of beauty. His buildings, like much–or even most–of the office space in Silicon Valley, are simply utilitarian. But as an economic indicator of sorts, the team's developments are a thing of beauty and clarity.

But the magazine isn't the only one proud of the developer. Andreessen, who married Arrillaga's daughter Laura in 2006, is even more reverential of the real estate tycoon. He routinely seeks Arrillaga's business advice and lauds him for not taking on debt and self-financing his projects. Most prominently, he admires his "faith" in Silicon Valley.

Arrillaga, those close to him say, believes [Silicon Valley's real estate] climb has much further to go. The demand is now coming overwhelmingly from businesses like Google, Apple, and LinkedIn–huge tech companies that are expanding their businesses and increasing employee headcounts, pushing the companies into a continual hunt for space. They are making gigantic bets on expansion in a way the developer (again, to hear colleagues tell it) has never witnessed, even during the 1990s dotcom boom.

"John just sees that as a very powerful thing," says Andreessen. "He has a deep and abiding faith in the Silicon Valley phenomenon."

Thanks to that "phenomenon," Andreessen sits on two fortunes: the one he made and the one he married into. I guess it's easy to tweetstorm about the poors when you're going to die rich no matter what.

Photo: Getty