Mellon Bank built the stately granite structure in 1923, but it was closed, sold and converted to a Lord & Taylor Department store in 2000. The city spent nearly $12 million to lure Federated Department Stores Inc. to the site, but it closed four years later when it failed to attract shoppers and has been vacant since.
PNC officials said the workers will be relocated from other spaces in and around the city.
J.J. Gumberg Co. bought the building in February 2005 in hopes of attracting another department store or other retail users to the space without success. The banking company hopes to close on a deal to buy the building next month.