In what is described as the largest Silicon Valley office space deal of 2013, Google has leased 500,000 square feet in Mountain View, near the company’s Googleplex headquarters. Under local government rules, the new space could house up to 2,500 workers. When it comes to Silicon Valley real estate, Google is nearly as dominant as it is in search. The company already has plans for a separate 1 million square foot campus on the grounds of NASA's Ames Research Center, which could house up to 5,000 workers. It's adding space in Sunnyvale and Palo Alto. Some observers wonder what Google will do with all that new office space. Is it planning for growth, consolidation, increasing cubicle sizes or some combination of the three? The company isn't saying, but a reporter familiar its real estate dealings says all signs point toward more Google hiring. “I think this is for expansion,” said George Avalos, who covers Google for the San Jose Mercury News. “The tea leaves say this is expansion, not just musical chairs.” Google isn't the only company snatching up prime Silicon Valley real estate. Avalos said Apple, Samsung, LinkedIn, Dell and Facebook are also increasing their footprints. Avalos contrasts these expansions to the Silicon Valley real estate rush of the late 1990s, during the Internet boom that eventually turned into a bust. So does real estate executive David Buchholz. He told the Mercury News that "the dot-com companies had a vision, but really had no products or sales. Today, it is good, solid growth." Google has not said when the new facilities will be occupied.