A little more about the project from HDR Inc, the architects of the project:

The design team developed a dynamic planning concept that, by allowing for a variety of work settings, saves a significant amount of space by facilitating mobility and choice, along with collaborative work environments.

The result:  the Agile Workplace is a community of workspaces created by a clearly defined “kit of parts” organized into a stimulating environment to encourage new ways of working. Instead of defining space as 250 sf per seat, the Agile Workplace allows 115 sf per user. The original space had seemed tight with 68 cubicle stations; the same area can now accommodate 120 employees — almost twice as many — in an attractive modern environment.

The Beginning – 164 South Park Avenue

Twitter’s first office was originally located within the offices of Obvious Corp., the company Twitter was born from. The space was a warehouse with tall ceilings and the classic startup look. At this point, Twitter hadn’t been around very long and many people were wondering just what the heck it was and why anyone would want to use it.

Growth Phase 1 – 539 Bryant Street

After some time, Twitter moved into its first office located just around the corner on Bryant Street. This space was similarly raw in nature, though with a style quite it’s own. Wall decals, huge amounts of natural light, and a set of green deer which would continue to inhabit their future spaces.

One important thing to note about this space is that it marks one of the company’s most trying periods that was full of huge service downtimes due to their spectacular growth.

Though Twitter moved out, Xobni has since moved in and made the space it’s own.

Growth Phase 2 – 795 Folsom Street

With their growth, Twitter once again upgraded spaces. While still a startup, they enlisted the help of designer Sara Morishige to help make the space playful, useful, and sustainable. Wall decals are used again, though much more company specific, with the use of a flock of birds. They also used a number of designs from local businesses.

Though the space initially seems fairly sparse in terms of decor and flavor, the space is given another upgrade that fills in many of the gaps. Both sets of images are below:

The Future – Market Square

What’s next for Twitter and its employees in terms of office space? Well it seems like the company decided to stay in San Francisco after famously receiving a tax break as well as agreeing to moving its offices to a less-than-popular part of town.

Their space will be some 200,000 square feet, gives them room for around 1200 employees, and gives them the option of snagging another 200,00 square feet if necessary.

These images and more at Business Insider.