Irony has crept into the architectural values of many Silicon Valley companies, as if the young royals of tech were relieving with a joke the embarrassment of finding themselves running multibillion-dollar businesses. At Twitter, though, the irony doesn’t creep; it charges like an ostrich.

Just outside the cafeteria, called “@birdfeeder,” a family of plastic, neon-colored deer stands near the couches, on which pillows bear the crocheted words “Home Tweet Home.” Irregular soft cubes serve as impromptu meeting areas. There are ample sticks and twigs on the walls and ceilings, as if nests under construction.

The company encourages informal meetings in this low-stress setting, hoping that it will help foster new ideas. Back in the business area, there are open-plan work spaces, along with individual file cabinets on rollers that can be moved to wherever an employee will next be working.

Here, as at many other tech companies, is a sense that nothing is permanent, that any product can be dislodged from greatness by something newer. It’s the aesthetic of disruption: We must all change, all the time. And yet architecture demands that we must also represent something lasting.

Quick meetings take place in booths that look as if they were lifted from an upscale diner, with banquettes for two or four. Near the executive offices are the kind of angular couches and chairs that Dick Van Dyke would be happy to use for a pratfall. What is notable is also what is missing. At Twitter, you must request a desk phone. Employees use their cellphones, and the company pays the bill — for all major types, though a company official had to check to see whether this included BlackBerry and Windows Mobile, since everyone seemed to be on Androids or iPhones.

The main dining area, across from the elevator bank, is also known as the Commons. Twitter styles itself as the “global town square” for all the public conversations it hosts, and it likes the openness of the area not just for chance meetings but also for weekly gatherings where Dick Costolo, the C.E.O., presides from a raised platform. Information sharing has become a hallmark of Silicon Valley companies, particularly when things are going well. It is another way of fostering the idea, borne in the programming world, that hidden data is actually more valuable when shared.