In June of last year, amid fierce fighting for control of the city of Mosul, ISIS fighters in Iraq laid waste to the Great Mosque of al-Nuri. It was a devastating blow to the city’s cultural and religious heritage; the mosque had roots stretching back to the 12th century, and its distinct, lopsided minaret stood over Mosul for more than 800 years. That loss can never be undone, but Iraqi officials are taking steps to move forward. On Sunday, Francesca Paris reports for NPR, the rebuilding of the mosque’s foundation began.

Abdulateef al-Humayim, president of the Sunni Endowment in Iraq, set the cornerstone in place during the weekend ceremony, accompanied by representatives of the European Union and United Nations. The laying of the foundation stone marks the inaugural step of a reconstruction project that is expected to take five years, according to the BBC. The first year will be spent documenting and clearing the site, and the next four will involve rebuilding the prayer hall, minaret and other buildings. It is not yet clear if the new minaret will have the signature tilt of the original; prior to the destruction of the mosque, experts had been worried that the leaning minaret was on the verge of collapse.

The reconstruction project is being supported by the United Arab Emirates, which agreed to contribute more than $50 million to what Unesco has deemed “the largest … cooperation to rebuild cultural heritage in Iraq ever.”

The great Turkic military ruler Nur al-Din ordered the construction of the mosque in 1172. Much of the original structure had disappeared by the modern era, but the minaret—nicknamed “al-Habda,” or “the hunchback”—managed to survive until the arrival of ISIS. The mosque was seized when militants took control of Mosul in 2014, and it was from the Great Mosque that that the group’s leader, Abu Bakr al-Baghdadi, declared a new Islamic caliphate.

But when Iraqi forces tightened their grip on the city, the militants blew up the mosque; footage released by the Iraqi military at the time showed the structure crumpling after explosives went off near its base.

The battle to retake the city from ISIS lasted months, and claimed the lives of thousands of civilians. Large swaths of Mosul were left in ruins. But in recent months, there have been signs that the city is starting to recover from the devastation. In October, an orchestra performed in Mosul for the first time since ISIS had been defeated there. A book festival in November drew thousands of people.

Unesco has launched an initiative to rebuild other heritage sites in the city, including a market, two churches, a Yazidi temple and a university library. According to initial government estimates, Mosul needs at least $2 billion in reconstruction aid.

The road to recovery will be long and difficult, but the laying of the first stone to rebuild the Great Mosque is a promising symbol of what is hopefully to come. Speaking at the ceremony, Unesco Iraq representative Louise Haxthausen called the destruction of the mosque a “moment of horror and despair.”

“Today,” she continued, “as we lay the foundation stone of the Nuri mosque, we are starting a journey of physical reconstruction.”