Nimrud, Iraq -- The Islamic State of Iraq and Levant (ISIL, also known as ISIS) blew up Nimrud on a spring day last year. A truck mounted with speakers drove through the dusty roads surrounding the ruins of the ancient Assyrian city beforehand, instructing local residents to open their windows so that the glass wasn't shattered by the shockwave of a massive blast. Black-clad ISIL fighters then placed barrel loads of explosives among structures, friezes and sculptures constructed more than 3,000 years ago, then detonated them in an eruption of earth and masonry that levelled most of the site and sent debris for hundreds of metres. Ahmed, 26, who lives in a nearby village describes it as being like an earthquake. "It was very strong," he recalls. "The land itself was shaking." Nimrud was founded in the 13th century BCE and is widely seen one as one of the world's great archaeological treasures, home to the palace of Assyrian King Ashurnasirpal II, with its giant stone depictions of winged guardians known as lamassu, as well as temples to deities Ninurta and Enlil. But the area was captured by ISIL when the group swept across a swathe of northern Iraq in mid-2014. The group views anything predating the Islamic era as idolatrous and has systematically destroyed and looted such ancient sites, as well as those belonging to religious minorities such as Christians and Yazidis, or of Islamic sects that don't correspondent with its beliefs. ISIL revelled in this destruction. A propaganda video released at the time recorded the explosion from multiple angles, while other footage shot outside Ashurnasirpal II's palace showed ISIL fighters using cutting tools and sledgehammers to destroy friezes, drills and earth movers to tear apart statues. But the true extent of the damage only became clear in mid-November, when Iraqi forces drove ISIL from the area as part of the six-week-long offensive to retake the second city of Mosul.

Almost 1,800 of Iraq's 12,000 registered sites were in territory held by the group, and the devastation of Nimrud has raised further fears among archaeologists about the future of other sites within Iraq, already ravaged by years of insecurity and war. Deputy Minister for Culture and Tourism Qais Rasheed estimated that 70 percent of Nimrud's historical sites have been destroyed. Looking at what's left, even that seems optimistic. The remains of sculptures and bas-reliefs remain are piled where ISIL left them in front of the palace. Elsewhere, the destruction seems absolute - much of the area is nothing but a huge field of rubble dotted by chunks of stone with cuneiform writing and the odd mud brick wall. A steady stream of tourists once provided local residents with income and employment. In the nearest village, a scattering of houses with an army post at the entrance, few envisage those days returning. "We feel sad, as a lot of people in the villages worked at Nimrud," said Amar, 23. "People would come from all over Iraq to visit this place and now it's gone." Layla Salih, an archaeologist, who was among the first to inspect the site after ISIL were expelled, describes her assessment as one of "awful destruction". Because it has not been further disturbed since the explosion, she adds that there may be at least some small reasons for optimism. "The good thing is that the rubble is still in the site. We thought we lost everything, but we may be able to rescue something after all." But there are currently no safeguards to ensure that the remains of these priceless relics remain where they are. As of last week, Nimrud was completely unsecured, vulnerable to looting of the kind that ravaged Iraq's archaeological sites both under ISIL and during the chaos that gripped the country in the aftermath of the US-led invasion of 2003. Fighting, meanwhile, is still ongoing nearby and the boom of explosions regularly echo around the ancient city. Salih is all too aware of the risks. "I'm worried about its protection," she says. "The battle is still going on in the area and things could be stolen or damaged by those who don't care for Iraq's heritage. That's a big concern for me." Abdulameer al-Hamdani, an archaeologist with the Iraqi State Board of Antiquities and Heritage, describes a programme of "first-aid conservation" designed to halt further damage. The immediate priority, he says, is reinstating guards previously employed by the board to look after the site. Other plans include fencing off the area, transferring parts of broken sculptures to a secure location and constructing shelters to protect damaged structures before the rainy season. Even if these moves are undertaken, however, the damage done to Nimrud remains part of a catastrophic and ongoing destruction of Iraq's cultural heritage. Much of this destruction took place immediately post-2003, when archaeological sites in the south were heavily looted, along with the national museum in Baghdad. Then, the damage was the result of a precarious security situation coupled with economic collapse and widespread unemployment, says Allison Cuneo, project manager with the American Schools of Oriental Research Cultural Heritage Initiatives (ASOR CHI), which works with the US state department to document, protect, and preserve the cultural heritage of northern Iraq and neighbouring Syria. ISIL was different. The group systematically attacked a number of historic relics, including those in Mosul museum, for propaganda purposes, while at the same time looting others and selling the spoils to smugglers. ASOR CHI's research suggests that around 300 sites have been damaged in the 12 months after ISIL invaded northern Iraq in June 2014, nearly all deliberately. Now, the worry is that further damage will be revealed as ISIL retreat. Sites under the group's control include the spectacular ruins of Hatra and Assyrian city of Ninevah. Of particular concern to Hamdani though, are many lesser-known smaller sites which may have been completely wiped out. "I'm really worried about these places in the countryside, not just the famous cities and towns ... they're hidden and we don't know what's going on there." Protecting both the big and small of Iraq's ancient sites and relics may be beyond the country's own state institutions, but for Hamdani, this is not just a local problem. "We have responsibility as archaeologists in Iraq, but so do my colleagues everywhere else," he says. "This is not Iraq's heritage, but the whole world's."