Joseph Muldoon, senior vice president of Binswanger, represented both the landlord and a majority of the tenants. Muldoon was only available for a quick comment, but mentioned he and his associates are reveling in their success.

"We're continuing to get deals done and that's because of all the improvements we've made and we're offering free rent," Muldoon tells GlobeSt.com. If a tenant signs a five-year lease with 1500 Walnut, the tenant receives six-months free rent. "We're not offering it much longer as we're rapidly approaching 90% occupancy rate."

Robert H. Wise Management Inc. took 3,665 sf; Hurley, Francis & Associates took 2,032 sf; and the Community Voter project took 600 sf. Opportunities Industrialization Centers International Inc. was represented by Colliers and leased 3,006 sf.

The typical floor size is 14,553 sf, and the higher floors offer panoramic views of the city. Taking rent at 1500 Walnut is $19.50 plus electric, which Muldoon said in the past was "an attractive number in this market."

The Center City building is graded class B because of its age, but the ownership has invested $8 million in capital improvements for a new façade, a new updated HVAC system, six high-speed elevators, renovated restrooms, lobby and common areas. The building also features a covered garage with 160 parking spaces. Muldoon earlier described the building as catering to smaller "boutique" tenant.

"I mean, what's not to like about new heating, bathrooms and elevators? The neat thing about these old buildings is that when they are fixed up they are just as nice, and more unique than the new ones," Muldoon told GlobeSt.com in early May.

1500 Walnut is near commuter rail systems such as the Broad Street Subway, Market-Frankford Line, the Regional Rail system and the PATCO Hi-Speedline.