In 2004 the historic 1930 trading floor, already substantially altered (and unused for more than two years), was demolished and its pits filled with concrete. It was renovated in a modern style and now is leased to a privately owned options trading firm. In 1980, the owners added a 23-story expansion to the south side of the building. It was topped by an octagonal ornament shaped similarly to the terraced trading pits and was designed in a postmodern style by Helmut Jahn. Colored black and silver, with a sunlit atrium on the 12th floor facing the south wall of the older structure, the annex provided a four-story granite lined agricultural trading floor, then the world's largest at . Even as the Sydney Futures Exchange and other markets were ceasing outcry trading, Mayor Richard M. Daley led the groundbreaking on January 17, 1995, for additional expansion into a five-story building to the east designed by architects Fujikawa Johnson and structural engineers TT-CBM. When opened in 1997, the $175 million structure would add of trading space and for a period again would house the world's largest trading floor. It was nicknamed the "Arboretum" by some in reference to expansion supporter CBOT Chairman Patrick H. Arbor. The expansion included price boards long and supported 12,000 computers, 6,000 voice devices, and 2,000 video devices requiring of cable. Collectively, the trading floors now encompass approximately . The logo of the CBOT represents a trading pit, and appears prominently on stonework facing Clark Street and on street-level barriers at the service entrance on Van Buren Street. The addition has a twelve-story atrium and melds historical and contemporary design with art deco references such as setbacks, central tower, symmetrical projecting wings, pyramidal roof and abstract cascade and scallop lobby design. Between the original and new buildings, where there was formerly a street, a wide street-level walkway connects the plaza on LaSalle Street to Van Buren Street in what would ordinarily be the building's first floor. Passing over the Van Buren Street elevated tracks, a green glass-enclosed steel-frame bridge connects the lower southwest corner of the 23 story addition to the Chicago Board Options Exchange (although this bridge was closed to pedestrian traffic in the wake of the September 11, 2001 attacks for security reasons). In 2005, the building underwent an extensive $20 million renovation directed by Chicago architect Gunny Harboe, whose restoration work included Loop landmarks the Rookery Building and Reliance Building.