CONTINENTAL TOWERS NAMED BOMA'S SUBURBAN CHICAGO
OFFICE BUILDING OF THE YEAR

LAKEWOOD, NJ, NOVEMBER 23, 2005 — Prime Group Realty Trust (NYSE: PGEPRB), a Chicago-based real estate investment trust (REIT) owned by The Lightstone Group, announced today that its Continental Towers office complex in Rolling Meadows, IL, was recently selected by the Building Owners and Managers Association (BOMA) as Suburban Chicago's "The Office Building of the Year" (TOBY) award winner for 2005-2006 in the 500,000 to 1 million square-foot category.

Continental Towers Building Manager Catherine Carlson said, "We are honored to have won this prestigious award for the second year in a row. This is a testament to the quality of our on-site professionals, proactive property management philosophy, and emphasis on tenant services. Congratulations to our entire team on this terrific recognition." Prime Group Realty Trust, which acquired its interest in Continental Towers in 1997, provides on-site property management, engineering and leasing services.

Continental Towers is a 975,000 square-foot office complex that houses 55 businesses, employing more than 2,200 people. Continental Towers was selected as the 2004-2005 TOBY award winner in this same category, as well as for the entire North Center Regional area, which includes Illinois, Indiana, Ohio, Michigan and Kentucky.

The TOBY award program, now in its 21st year, is commonly recognized as the most prestigious and comprehensive program in the commercial real estate industry. Participants are judged on the effectiveness of their overall management in 11 categories, including community impact, tenant relations, energy management, emergency preparedness and training for personnel.

Continental Towers is located on a 34-acre site in the Woodfield area at the southeast corner of the Northwest Tollway (I-90) and Golf Road (Route 58) just east of Route 53. The complex features three 12-story office towers of approximately 280,000 square feet per tower. Above ground and underground walkways connect all three buildings with a three-story, glass-enclosed 133,487-square-foot retail concourse. The entire office complex, completed in 1982, is 30 miles northwest of Chicago's Loop and 10 miles northwest of O'Hare International Airport.

The office buildings feature floor plates of approximately 23,682 square feet, white marble lobbies, 25-foot by 25-foot bays, 24-hour staff, centralized security systems, closed-circuit-television monitoring systems, around the clock key-card access, state-of-the-art telecommunications systems and Internet connectivity, and surface and executive underground parking for 2,949 cars.

BOMA of Suburban Chicago was founded in 1972 to represent owners, managers and designated representatives of office properties in the greater Chicago suburban area including Cook, DuPage, Kane and Lake counties; Rockford, IL; and Merrillville, IN. The association's 300 members currently represent more than 57 million square feet of office space in commercial office buildings, government buildings, medical facilities and corporate headquarters. The organization is an affiliate of BOMA International, which was founded in 1970 and currently has approximately 18,500 members in 100 local associations representing nine billion square feet of quality commercial space globally. For more information, visit www.bomasuburbanchicago.com or www.boma.org.