HARI SREENIVASAN:

But first: The de facto capital of the Islamic State, Raqqa, in Syria fell yesterday to U.S.-backed forces.

However, the largest city the militants once held was Mosul in Iraq. They were ousted from it in July after a brutal 10-month-long fight that killed thousands.

Now a new major task: finding and destroying the ISIS mines, booby-traps and bombs that litter the city.

Special correspondent Marcia Biggs reports from Iraq.