We got an insane tip that's going to blow your Monday morning socks off: LinkedIn is about to ink a downtown deal to take an entire building. (Makes it a lot harder to crash their holiday party.)

We caught wind of this monster lease from an incredibly reliable source, and the deets are as follows: LinkedIn—not Box, as rumor had it—is going to sign a full-building deal for Tishman's new 26-story tower at 222 Second. The Mountain View-based networking giant already sits on several full floors totaling about 135k SF at One Montgomery Tower in the Financial District. A month ago we broke the news that LinkedIn was on the prowl for a couple extra thousand square feet in the city. The 452k SF tower coming to the southwest corner of Howard and Second has been years in the making: The site was purchased in 2006 and received full entitlements in December 2010.

The Thomas Phifer-designed tower will have a steel and concrete frame with a glass curtain wall and house 447k SF of office space, 5k SF of retail, and 8,500 SF of public space. In January the job search company was pursuing a large lease at 235 2nd—backfilling space CBS was going to vacate—but that deal fizzled once CBS pulled out of 505 Howard (blame it on Colbert) and LinkedIn had to go back to square one with its space search. The gigantic deal means LinkedIn is following other Silicon Valley trailblazers like Google who want to please young workforces with urban offices. LinkedIn's broker is Colliers.