(CNN) For centuries, the massive Assyrian city in Northern Iraq lay buried beneath the sands of time, forgotten by history.

Archeologists first began excavating Nimrud -- built nearly 3,000 years ago -- in the 1840s. In the decades that followed, they unearthed priceless treasures from the city, including palaces adorned with unique frescoes and giant sculptures, that offered a window into Iraq's glorious past.

Last year, ISIS blew up the ancient walled city.

The terror group released disturbing footage of the destruction. Militants with electric drills and sledgehammers smashed statues and tore holes in the walls. Bulldozers razed structures to the ground. The last frame of the video captures a massive explosion and a cloud of smoke and dust.

UNESCO, the United Nations Educational, Scientific and Cultural Organization, described the deliberate destruction of Nimrud as a "war crime."

On Sunday, Iraqi forces liberated the village of Nimrud and the site of the ruins as part of the ongoing battle for Mosul, ISIS' last major stronghold in Iraq, according to Col. Mohammed Ibrahim, a spokesman for Iraq's Joint operations command.

Nimrud includes a town and a village adjacent to the ruins. While the village is now under control by Iraqi forces, clashes are still underway to retake the town, less than a mile west of the ruins, Col. Ibrahim told CNN. Nimrud is 20 miles (30 km) southeast of Mosul.

Nimrud and Nineveh

Nimrud and nearby Nineveh are the sites where two Assyrian kings, Sennacherib (704-681 B.C.) and Ashurnasirpal II (883-859 B.C.), recorded successful military campaigns on the walls of their palaces, according to the World Monuments Fund, a group dedicated to saving the world's most treasured places.

Relief of a human-headed winged lion in Ashurnasirpal II's palace in Nimrud in northern Iraq.

"The palaces of Sennacherib at Nineveh and Ashurnasirpal II at Nimrud are vestiges of the political, cultural and artistic height of the Assyrian Empire," the WMF says on its website under the heading, "Why it Matters." The group had helped preserve the treasures at Nimrud following the 2003 Iraq war.

Nimrud flourished between 900 B.C. and 612 B.C. Buildings there "have yielded thousands of carved ivories, mostly made in the 9th and 8th centuries B.C., now one of the richest collections of ivory in the world," according to Encyclopedia Britannica's website.

The famous British mystery novelist Agatha Christie accompanied her husband, archaeologist Max Mallowan , at his excavation in Nimrud and helped clean some of the ivories.

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This is not the first time that ISIS has targeted cultural and ancient sites in Iraq and Syria. The terror group took over the ancient ruined city of Hatra in 2014, using it to store weapons and ammunitions. It has destroyed libraries, palaces and churches, and blown up shrines such as the tomb of Jonah , a holy site said to be the burial place of the prophet Jonah, and a key figure in Christianity, Judaism and Islam.

Last year ISIS militants using sledgehammers obliterated stone sculptures and other centuries-old artifacts in the Mosul Museum.

"ISIS continues to defy the will of the world and the feelings of humanity," Iraq's Ministry of Tourism and Antiquities said in a statement last year, condemning the destruction in the Mosul museum.

"Letting these lost gangs go without punishment will encourage them to destroy humanity's civilization, the Mesopotamian civilization, inflicting irreversible priceless damages and losses."

Other precious monuments destroyed by war

Iraq's neighbor Syria is also a treasure trove of archaeological sites, many of which have been reduced to rubble during that country's ongoing civil war.

ISIS is part of a puritanical strain of Islam that considers all religious shrines -- Islamic, Christian, Jewish, etc. -- idolatrous.

It is not the only militant group bent on the destruction of the symbols of ancient life. In 2001, the Taliban blew up giant statues, the Buddhas of Bamiyan, in Afghanistan despite international pleas to spare the country's pre-Islamic relics.

The destruction has disturbed many scholars and historians.