Papadakis says the donor is a university trustee who wants to remain anonymous.
The gift allows Drexel to acquire and renovate a pair of buildings that will extend the footprint of its campus in West Philadelphia.
School officials say they need to raise at least $30 million more to complete the design center. It will house several programs, including architecture and interior design.
Drexel is a private university that enrolls about 13,000 undergraduates.