Nimrud, which Iraq said was bulldozed Thursday by jihadists, was once the jewel of Assyria, home to a treasure considered one of the biggest archaeological finds of the 20th century.
On Thursday, the Islamic State group "bulldozed" the ancient ruins of Nimrud, which lie on the Tigris about 30 kilometres (18 miles) southeast of Mosul, according to the antiquities ministry.
Nimrud, founded in the 13th century BC, is one of the most famous archaeological sites in a country often described as the cradle of civilisation.
"Nimrud was the capital of Assyria, during the new Assyrian era," said Abdulamir Hamdani, an archaeologist from Stony Brook University in New York.
The city, which is on UNESCO's tentative list of world heritage sites, is the later Arab name given to a settlement which was originally called Kalhu.
The ancient city was first described in 1820 and plundered by Western explorers and officials over subsequent decades. It was also looted and damaged during the 2003 US invasion.
The extent of the damage done to Nimrud by the jihadists is unclear because guards and antiquities officials have not yet been able to assess it.
Most of Nimrud's priceless artefacts were moved long ago to museums in Mosul, Baghdad, Paris, London and elsewhere but giant "lamassu" statues -- winged bulls with human heads -- and reliefs were still on site.
The destruction comes a week after a video was released in which IS militants wielding sledgehammers are seen gleefully smashing statues in the Mosul museum.
Many of the artefacts destroyed in the video came from Nimrud.
"It's really a very important site in the history of Mesopotamia," said Hamdani. "Many of Assyria's greatest artistic treasures came from this site."
The "treasure of Nimrud", unearthed in 1988, is a collection of 613 precious stones, gold jewels and various ornaments which some archaeologists described as the most significant discovery since Tutankhamun's tomb in Egypt in 1923.
The treasure, which dates back to the Assyrian empire's heyday around 2,800 years ago, was briefly displayed at the National Museum in Baghdad before Iraq invaded Kuwait.
It was then hidden and its fate remained unknown until it was discovered in 2003, soon after US-led troops toppled Saddam Hussein's regime, in a bombed out central bank building.