Islamic State (Isis) posted online a video of what was said to be Mosul residents celebrating the group taking the Iraqi city of Ramadi.
The video, posted online on Monday 18 May and said to be filmed the day before, showed large crowds of people waving Islamic State flags and cheering.
Children can be seen in the video waving flags and celebrating with guns alongside large groups of young men.
The taking of Ramadi was the biggest victory for IS in Iraq since security forces and Shi'ite paramilitaries began pushing the militants back last year, aided by coalition air strikes.
One man shown, who is not named, said IS's success in Ramadi was just the start of its conquest over other major cities.
"As the Caliph said the day before yesterday, the conquest of Anbar is just the beginning of the conquest of Baghdad, Najaf and Karbala," he said.
"We will be smashing idols and shrines over the heads of their owners God willing. Now the conquest has begun, now the fighting has begun," he added.
Another unidentified man also said the victory was a sign of things to come.
"We congratulate the Caliph Abu Bakr al-Baghdadi and all Muslims in the land of the Caliphate, in the Islamic State, for the liberation of the land of Ramadi and God willing, we are heading to Baghdad and Karbala, and we will smash them all with God's will," he said.
Around 500 people have been killed in the fighting for Ramadi in recent days and between 6,000 and 8,000 have fled, a spokesman for Anbar's provincial governor said on Monday.
The city's fall marked a major setback for the forces ranged against IS: the US-led coalition and the Iraqi security forces, which have been propped up by Iranian-backed Shi'ite militias.
It was also a harsh return to reality for Washington, which at the weekend had mounted a successful special forces raid in Syria in which it said it killed an IS leader in charge of the group's black market oil and gas sales, and captured his wife.
Mosul itself, which is positioned in the north of Iraq, remains under the control of IS.