Sometime before 10:45 a.m. Saturday, National Park Service rangers stopped the man after receiving reports that he was threatening to blow up the Liberty Bell.
Two black backpacks were found in front of the Liberty Wheels wheelchair and scooter rental shop at 714 Market St. a half-block away.
Police arrived around 10:45 a.m. and closed off Market Street between Seventh and Eighth Streets.
Shortly after, a member of the Philadelphia Police Department bomb squad began examining the backpacks. The results came back negative for hazards, a bomb squad officer said.
Market Street reopened to pedestrians and traffic around 11:45 a.m. The Liberty Bell remained open throughout.
Agents from the Bureau of Alcohol, Tobacco, Firearms and Explosives also responded.
Special Agent Frank Burton Jr., spokesman for the FBI's Philadelphia division, said the joint investigation was being conducted by Philadelphia police and the FBI because the Liberty Bell is a federal landmark.
Contact Jonathan Lai at 856-779-3220, email@example.com, or follow on Twitter @elaijuh.