Twitter is putting all its eggs in one building. The social media giant just signed to take all of 1 Tenth.

Twitter will occupy the new 338k SF building next to its HQ in Q4, Shorenstein's Tom McDonnell told us this morning. His colleague Jim Collins is snapped above, showing us a rendering of the building back in November. The space will be delivered to Twitter in a couple months for the newly public company to build out. It's unclear how many employees will be able to squeeze inside, but Tom notes that Twitter currently has a mix of collaborative areas and fairly dense benching stations. (We've squeezed deep meaning into 140 characters, so we bet they're good with space.)

He said there was "significant interest" in the building aside from Twitter, from tech and ad firms. Those talks, of course, went dead once Twitter amped up its interest. Twitter will take floors two and five through 10; three and four are on hold for Twitter for the short term. The 1970s-era, 10-story building was completely redeveloped and will be connected to 1355 Market via a landscaped plaza. JLL reps Twitter.