Police say numerous fires were set along the 1700 block of Ranstead Street, continuing for a few blocks to 19th and Sansom streets near the Philadelphia Stock Exchange.
Fires were also reported on the 1700 block of Chestnut Street.
Police took the man into custody at 3 a.m. near 15th Street and JFK Boulevard.
His identity has not been released.
No charges have been filed so far.