SAN FRANCISCO Apple Inc. has 1 Infinite Loop; Genentech Inc. has 1 DNA Way. But Facebook Inc. now lays claim to Silicon Valley's premier vanity address: 1 Hacker Way.

After journeying from a Harvard University dorm room to a rented house in Palo Alto, Calif., to a series of temporary corporate offices it quickly outgrew, the 8-year-old social networking giant has set down permanent roots just in time for its initial public offering.

And its splashy new campus in Menlo Park, Calif., has quickly become the envy of its Silicon Valley neighbors.

Last week Facebook filed papers to sell its stock to the public in an offering that could raise $5 billion and up the company's value as high as $100 billion.

On a recent afternoon, the 57-acre campus hummed expectantly as more than 2,000 employees, about half of whom will probably become instant millionaires, were still settling into their new digs. In all, the company has more than 3,000 employees in 35 offices in 20 countries.

Thirty miles south of San Francisco on the edge of tidal mud flats and salt marshes, the nine-building complex has room for up to 3,600. The company seeks approval from Menlo Park to boost its capacity to 6,600. It has campaigned for months to win over Belle Haven, the largely Mexican-American neighborhood nearby, to clear the way for its expansion.

It's all part of co-founder and Chief Executive Officer Mark Zuckerberg's drive to create an urban oasis for staffers, part of its take-no-prisoners effort to one-up its chief rivals, such as Google, in the wars for top engineers and executives.

"We are creating the new urban place to work," said Facebook real estate chief John Tenanes.

Little remains of the more staid former Sun Microsystems, which favored private offices, wall-to-wall carpeting and glass-walled conference rooms.

Facebook has ripped open ceilings and walls to expose steel girders and ductwork, peeled back carpets to concrete floors polished with swirls. There are no cubicles or offices, not even for Zuckerberg, just long tables with super-high-IQ workers plugging away.

That means Facebook can accommodate more staffers on the 1 million-square-foot campus than Sun did, Tenanes said. Sun dedicated about 270 square feet to each staffer, while Facebook dedicates just 150 square feet, Tenanes said. That helps Facebook use about 30 percent to 35 percent less energy, he added.

"Hack" has been doodled and scribbled on walls covered floor to ceiling in chalkboard paint in the real-life equivalent of Facebook users' walls. (At the entrance to Facebook's campus stands a giant wood sculpture that Facebook staffers created during a recent hack-athon that spells out "hack," Facebook's motto of moving fast and breaking things.)

Graffiti artist David Choe tagged the walls of the building that houses Zuckerberg and other Facebook executives. Breakaway spaces that Facebook calls "cozies" pop up everywhere for spontaneous meetings. Micro-kitchens stocked with typical Silicon Valley fuel - Red Bull, chips and other snacks - are strategically placed throughout the buildings so that no employee ever goes hungry. Vending machines dispense free soda or computer accessories.

Employees can even hit the full-service bar on Friday afternoons. The Shady Lady features an old-school vinyl bar purchased on classified website Craigslist. Or if they are feeling nostalgic, they can sit down at a gray, midcentury-era metal desk topped with a Royal typewriter.

The main attraction, especially around noon, is the first of two cafes to dish up gourmet grub from top chefs. It sports the design of a circuit board to efficiently and quickly flow 2,000 people in and out in an hour and change. Food carts serving such delicacies as Korean tacos roam the campus.

One thing that still lingers from Sun Microsystems: All the doors. Facebook reused them, and some still bear the logo of the company that used to burn so brightly in Silicon Valley but was bought out by Oracle Corp. in 2010. It's a subtle reminder of what can happen to companies that don't stay on top of their game.

Top 10 surprises in the Facebook IPO

From Facebook's filing for its initial public offering last week:

10. How many users? Facebook now has 845 million users - 45 million more than the company reported in September - and 483 million daily active users. Those users generate 2.7 billion daily "likes" and comments, many of which are about the 250 million photos uploaded each day.

9. How many relationships? Facebook has a stunning 100 billion relationships on its site - one for every dollar of the highest estimate of its valuation.

8. How much are they making? The company brought in $3.7 billion in revenue last year and $1 billion in profit. Based on Facebook's own revenue and user data, every monthly user on the site is worth about $4.62.

7. Zuckerberg's security detail: Founder Mark Zuckerberg has a "comprehensive security program" that covers security personnel and the installation of a security system at his home. The security costs are included in his overall compensation.

6. Plans for global domination: Facebook is casting a hungry eye overseas, and more and more of its revenue is coming from nondomestic sources. Facebook is available in 70 languages and is looking closely at Brazil, India and China. The company is also looking to make further inroads into countries such as Russia and Japan where Facebook faces stiffer social networking competition.

5. Growth: The days of Facebook's fastest growth - at least in the United States - appear to be behind it. U.S. user growth trails the rest of the world, likely because the company has already penetrated such a high percentage of the American market.

4. Mobile: A big surprise in Facebook's filing was that the company appears to have a problem with mobile. The company doesn't have display ads on its mobile products now, and said that it worries the trend toward mobile could hurt its bottom line. If the company can find a clever, non-intrusive way to use all of its data for mobile marketing, it will be a huge deal. But control over the ads is a problem - Facebook doesn't have its own phone, carrier or operating system, any of which could affect how the company is allowed to display ads.

3. Sheryl Sandberg: Losing chief operating officer Sheryl Sandberg was listed as a risk factor in the IPO paperwork, a surprising if not shocking mention for the former Google executive who's become a very important part of the social network. There's been speculation that Sandberg, who has a background as a Washington insider, may consider going into politics.

2. Zuckerberg's succession plan: The S-1 filing revealed that Zuckerberg will be able to appoint someone to take over his controlling shares. From the filing: "In the event that Mr. Zuckerberg controls our company at the time of his death, control may be transferred to a person or entity that he designates as his successor. As a board member and officer, Mr. Zuckerberg owes a fiduciary duty to our stockholders and must act in good faith in a manner he reasonably believes to be in the best interests of our stockholders."

1. Zynga, Zynga, Zynga: In its S-1 filing, the company revealed that its partnership with Zynga accounts for 12 percent of its total revenue - a very surprising amount for a single company. That's around $445 million of the company's 2011 revenues. The money comes from the cut that Facebook receives through Zynga's in-game purchases and advertising. Washington Post