It happened at the intersection of 38th and Spruce in the University city section around 9:30 a.m.
The man reportedly fell from a scaffolding.
The man, who is between 20 and 30 years old, was rushed to the Hospital of the University of Pennsylvania in critical condition with head injuries.
Police are now investigating how this fall happened.
The name of the man who was injured has not yet been released.
