Completed in 1937 as the Western Furniture Exchange and Merchandise Mart, the Art Deco monolith that dominated the corner of Market & 10th Street is an exchange once again. But rather than only house transactions of physical commodities,Market Square, as it is now called, is a bazaar of opinions and conversations as the new global headquarters of Twitter. Nicknamed as “TWOffice 4.0″ by some, the spacious setting takes up the upper floors of Market Square. Conveniently situated right between SOMA and the Civic Center, it’s also part of an urban renewal project that’s focusing on a debilitated part of San Francisco. And though there are plenty of amenities, such as the “@BirdFeed” employee cafeteria, yoga & meditation room, and rec. room with ping-pong table and arcade, a must for any tech start-up, the new accommodation is surprisingly sparse in decoration, maybe because most programmers have a nomadic working habit–or perhaps Twitter is thinking of a bigger office space already? Images via: Troy Holden

P.S.- Did you know the name of the Twitter bird is “Larry”?