Chicago, May 20, 2008 – The international engineering design firm of Thornton Tomasetti, Inc. has signed a long-term lease for 25,045 square feet of office space on the 15th floor at 330 N. Wabash Avenue (the former IBM Building), in downtown Chicago.

“Our business is growing, especially internationally,” said Daniel Marquardt, Thornton Tomasetti managing principal based in Chicago. “Having our Chicago office in an architecturally significant building is hugely exciting for our staff and clients.”

The firm expects to take occupancy in January 2009 when it will be relocating from 14 E. Jackson, where it has leased 15,000 square feet since 1999. Interior design of the new Thornton Tomasetti office will be led by Garafalo Architects, in association with Powell/Kleinschmidt. In the design and operation of the new space, Thornton Tomasetti will seek certification for Leadership in Energy and Environmental Design (LEED).

Owned by Prime Group Realty Trust, the 1.5-million-square-foot building, designed by Mies Van der Rohe and built in 1971, was recently designated a Chicago Landmark and was approved for Class “L” real estate tax status earlier this year when floors 2-13 were sold to a joint venture between an affiliate of Oxford Capital Group, LLC and LaSalle Hotel Properties, a hotel real estate investment trust, which plans to open a first-class hotel on those floors by early 2010. The new Class “L” status will significantly reduce property taxes for both the hotel owners and the office tenants for twelve years when it goes into effect in 2010.

Peggy McTigue, Senior Vice President at CB Richard Ellis, Inc., represented Thornton Tomasetti in its lease negotiations and Anita Pallardy, Senior Vice President of Prime Group Realty Trust, represented the landlord.

“We are thrilled to have a prestigious engineering firm like Thornton Tomasetti select our building for its new Chicago office,” said Prime Group Realty Trust President and CEO Jeff Patterson. “Thornton Tomasetti is an engineering design firm that works on some of the most innovative buildings internationally, and we are excited that people from all over the world will be coming to their offices, which will only serve to enhance the international stature of 330 N. Wabash Avenue.”

Mr. Patterson added that with the re-development of the lower floors into a hotel, the re-design of the mechanical systems on many of the office floors, the building’s views and location along the Chicago River, and its proximity to the new Trump Tower, 330 N. Wabash has become one of the most sought-after existing office buildings in downtown Chicago.

About Thornton Tomasetti (www.ThorntonTomasetti.com)
Thornton Tomasetti provides building engineering services to clients worldwide on projects of all sizes and complexity. From the tallest buildings and the longest spans, to innovative building systems and materials, the firm is committed to creating the best solutions through its technical ingenuity, pursuit of excellence, and responsiveness to client needs.

Founded in 1956 as Lev Zetlin & Associates, today Thornton Tomasetti is a 650-person organization of engineers and architects, collaborating from offices across the United States and in Hong Kong, London, Moscow, and Shanghai. Services cover structural design, building evaluation, and remediation to optimize building efficiency and performance. Thornton Tomasetti mobilizes rapidly to provide disaster response investigations, and delivers expert consulting services and testimony for legal and insurance purposes.

About CB Richard Ellis
CB Richard Ellis Group, Inc. (NYSE:CBG), a Fortune 500 and S&P 500 company headquartered in Los Angeles, is the world’s largest commercial real estate services firm (in terms of 2007 revenue). With over 29,000 employees, the Company serves real estate owners, investors and occupiers through more than 300 offices worldwide (excluding affiliate offices). CB Richard Ellis offers strategic advice and execution for property sales and leasing; corporate services; property, facilities and project management; mortgage banking; appraisal and valuation; development services; investment management; and research and consulting. CB Richard Ellis is the only commercial real estate services company named one of the 50 “best in class” companies by BusinessWeek, and was also named one of the 100 fastest growing companies by Fortune. Please visit our Web site at www.cbre.com.

Contact
Thornton Tomasetti – 917-661-7800
James M. Kent, JKent@ThorntonTomasetti.com

CB Richard Ellis – 312.935.1475
Angela Burrows, angela.burrows@cbre.com