Firefighters were called to Independence Hall early Sunday morning after smoke was found inside the basement.
Officials say the smoke was spotted shortly after 5 a.m. at the historic building on the 500 block of Chestnut Street. Firefighters were able to place the small fire under control around 5:30 a.m.
No one was injured during the incident.
No damage was reported.
Officials have not yet revealed the cause of the fire.
This story is developing. Stay with NBC10.com for updates.