The one- and two-bedroom apartments are renting for $1,500 to $3,000 a month.
Blatstein called the project "transformational."
"Where others may have seen an older, vacant government office building, we saw an opportunity to create attractive apartment dwellings for a wide demographic of Philadelphians," he said.
The project was financed with bank loans, plus "less than $10 million" in historic tax credits through the state, Blatstein said.
The building, which dates from 1957 and is characterized as Midcentury Modern architecture, was placed on the National Register of Historic Places in 2010.
Eight years ago, Blatstein put down his first stakes on North Broad, developing Avenue North on the southern edge of the Temple University campus. That $220 million project included student apartments as well as a movie and retail complex.
The Tower Place apartments are being developed in two phases for a total of $180 million. The second phase will start in five years and include a new 18-story apartment tower, plus two stories of retail space, Blatstein said.
Several nearby projects also are moving forward.
On Saturday, the School of the Pennsylvania Ballet will hold classes for the first time in new studio space at Broad and Wood Street.
A few blocks north, Project HOME has started construction on a $16 million project for 55 apartments at Broad and Ridge Avenue.
Across the street, developer Eric Blumenfeld is trying to finalize financing to restore the derelict Divine Lorraine Hotel into apartments.
And at Cecil B. Moore Avenue, Temple will start housing 1,300 students in a $216 million dormitory this fall.
"North Broad Street used to be the stepsister of South Broad," said City Council President Darrell L. Clarke, who attended the ribbon-cutting at Tower Place. "But I have to tell you, North Broad is where it's at."
Clarke, whose district includes all of the projects, said other developments are in the works, but are not yet public. "We should have the announcement of additional action on North Broad Street relatively soon," Clarke said.
Contact Jennifer Lin at 215-854-5659 or firstname.lastname@example.org, or on Twitter @j_linq.