Twitter's move to its new offices this summer kept the technorati buzzing for months. Granted, some of that attention was fixed upon the sizable tax break the company got from San Francisco for staying in the city. But the end product of a minimalist build-out of the 215,000-square-foot space justifies much of the hype: It includes a spacious cafeteria (dubbed "@birdfeeder"), a Zenlike yoga room, and a rooftop deck for employees to bask in the sun--and even to garden.

The company, which now has more than 1,000 employees based in San Francisco, had long outgrown its previous headquarters, which grew crowded. "I could smack the person next to me in the face if I moved too quickly," says Melanie Linehan, a former employee.

Apart from gaining additional space, Twitter, which had previously subleased its offices from other tenants, sought a relaxed environment that it could finally put its own stamp upon. It found just that in a historic art-deco building that formerly housed a furniture wholesaler.

Choosing headquarters in the gritty Mid-Market district of San Francisco initially raised a few eyebrows. Twitter positioned the move as a way to jump-start the economic revitalization of the area. But the initial skepticism has quickly turned into awe. "There's something special about the Twitter office," Linehan says.

That's in no small part thanks to its design, which was developed by two San Francisco firms, IA Interior Architects and Lundberg Design. Inc. senior reporter April Joyner spoke with Nancy McEvers Anderson of IA Interior Architects about turning Twitter's aspirations for its new headquarters into reality.

What were your main goals for the design? 
Twitter came to us as a start-up looking to be grown-up. Before, it had always had space that was subleased from a client. So this was an opportunity to look for a home.

Before we even started designing, we all sat down and had a visioning session. They listed the things that were important to them; words like sustainable and rustic elegance came up. We took pieces from the old building and reused them--we didn't want the office to look like a polished corporate headquarters. We used environmentally sensitive finishes.

One of the words that also came up was humble, which is an interesting choice. Twitter is not Google--it's still a start-up. So you won't see every primary color in the office. We went for something understated. 

They also wanted a space that would provide a sense of community. They specifically mentioned wanting a space that the staff would love to come to.

How did you incorporate the historic aspect of the building into the design?
There were a lot of space considerations. The office is actually in two connected buildings from the 1930s and '40s. There was a sensitivity to be honest to the original materials of the structure. Apart from being sustainable, that means not making the building something that it's not; celebrating what's there in the existing architecture.

The old building had a sea of columns. There was a concrete floor and a deck. There are spaces in the building that have relief cornices and moldings, and we didn't look to cover those things up. We wanted everything to be honest and open.

The rooftop deck is a really nice space. How did you come up with the idea for it? 
The old Furniture Mart building was built with an individual furniture showroom on the ninth floor. Later, another section was built onto the original structure, but it didn't relate to the original, historic design structure. So the last owner peeled it off, and that's where we designed the roof deck.

In the adjoining space, there was a double-high deck, 26 feet--it took up two floors. Originally, it was an auditorium. That's where the kitchen, café, and the commons area are now. We put in acoustical panels, and then we broke through the concrete wall and put in a door that leads to the outdoor deck. So it's an indoor and an outdoor space. The roof has a garden, and there's outdoor seating.

What was your approach to the workspaces?
A lot of it is rightsizing--making sure there is the right complement of space to people. There are enclosed meeting spaces for more formal meetings. But there are also spaces where people can meet informally. So what we did is create a large corridor that marches down through the front of the commons area and put in soft foam seating. We used a furniture system called Gather. We wanted to create a large, welcoming space. During the early part of the project, we called it Broadway, because it was such a wide corridor.

We also added booths for employees to collaborate in, like a café environment. Some are built for one-on-one working, and some are built for four. It's like they're in a cocoon--they're surrounded by fabric-wrapped panels. We purposely placed the booths in areas to help us to break up the floor plate. We created "neighborhoods" based upon these open office workstations, so there would not be these large seas of workstations.

Did the space present any design challenges? 
We were concerned about the large floor plate. Bringing light to the middle was extremely important. We wanted to make sure everyone could enjoy natural light. There are no private offices--there are conference rooms in the center of the building, but they are in a glass box. So we were able to take advantage of the natural light and let it penetrate through the building. There is a lot of glass used throughout the office.

There's been a lot of discussion about Twitter's move to the Mid-Market district. Did the neighborhood factor into the design at all?
The building they chose is a great site, and it fits the company's goals to be socially responsible. The community is being gentrified now, but it was not very welcoming for a long period of time. So having Twitter established there is a key entry point. In the reception area, there's a view of the chambers of City Hall. That's a great reminder of its social responsibility.