"You can't improve upon AT&T's credit and name," Anita Pallardy, Prime Group Realty SVP, tells GlobeSt.com. "DeStefano is expanding globally and they're a good, professional firm. These tenants join other internationally-recognized tenants in the building, like Perkins+Will and Thornton Tomasetti."

Mark Keebler and Brad Serot, with CB Richard Ellis, represented DeStefano + Partners in the lease. George Kotrogiannis and Kurt Kittner, with Jones Lang LaSalle, represented AT&T Corp. Asking lease rates range from $18 to $28 triple net in the 1.1-million-sf office building. It is now 90% leased with about 118,000 sf of office space remaining vacant.

The building's occupancy rate will take a serious hit in 2010, when Jenner & Block LLP vacates the tower rise portion - 371,944 sf in floors 37 through 47, or about a third of the building. "They're moving to a building directly to the west," Pallardy says. "This creates a phenomenal new anchor tenant opportunity in some of the best space in Chicago." Pallardy says Prime Group has already seen substantial interest in the space.

Prime Group has also recently refinanced the building. "Knowing we're going to be losing our anchor tenant, we have money in the bank today and in light of credit markets, that puts us in a stronger position financially than some of our competitors," Pallardy says.

The building, completed in 1971 as Mies van der Rohe's largest and last building designed in the country, was recently given landmark status by the city of Chicago. This designation provides tenants reductions in real estate tax assessments. Tenants are also provided shuttle service to and from Metra train stations, a reduced postage program, a 900-stall parking facility and lobby kiosk offering food and coffee.

Earlier this year, Prime Group vertically subdivided the building, selling floors two through 13 to investors who plan to develop a hotel in the space, which is expected to open in 2010. "It completely is a grand-slam relative to our redevelopment efforts on the building," Pallardy says. "It's going to be boutique and the hotel market is still hot and will remain that way even in light of the economy, especially with Chicago chasing the Olympics."