The city's water department says the main broke Saturday afternoon, flooding Walnut Street as shoppers and tourists had been packing the area during the busy shopping season. The break has detoured traffic and created headaches in the area.
Stores are still open on the block, but visitors have to drive and park in other areas.
The water department says the main was back in service Sunday morning, but Peco and Philadelphia Gas Works need to check for any other infrastructure damage.
City workers also need to repave the street, so it's unclear how long it will be closed.