Media reports say Islamic State (IS) extremists on June 21 blew up Al-Nuri Grand Mosque in Mosul.

The mosque, built in 1172, and its minaret known as “the hunchback” were chosen as the venue where IS leader Abu Bakr al-Baghdadi in July 2014 declared himself “caliph” of what he hoped would be a militant empire growing out of Iraq and Syria.

The New York Times reports that  on Wednesday night, with the terrorist group on the cusp of losing control of Mosul and with it its claim to a caliphate straddling the border of Iraq and Syria, Islamic State fighters packed the building with explosives and took it down.

The destruction of the mosque and minaret — which has dominated Mosul’s skyline for centuries and is pictured on Iraq’s 10,000 dinar bank note — is another blow to the city’s rich cultural heritage and its plethora of ancient sites that have been damaged or destroyed during three years of Islamic State rule.

For residents of Mosul and those who care about Iraq’s history, the destruction was yet another painful loss, after so many years of the Islamic State violently erasing a region’s history.

IS's Amaq news site claimed after the blast that the mosque was destroyed by a U.S. air strike, but that claim was quickly denied by the anti-IS coalition, which said no strikes were carried out in the area on June 21.

The mosque was named after Nuruddin al-Zanki, a nobleman who fought the early crusaders from a fiefdom that covered territory in modern-day Turkey, Syria, and Iraq.

It was built with seven bands of decorative brickwork in complex geometric patterns ascending in levels towards the top, similar to designs found in Persia and Central Asia.

The minaret started listing centuries ago and was long considered an endangered monument.

Before the Islamic State took control of Mosul, UNESCO had begun an effort to protect and rehabilitate the minaret.

According to The Independent, U.S. Army Major General Joseph Martin, a senior U.S. commander in the battle against IS, called the mosque's devastation “a crime against the people of Mosul and all of Iraq" and "an example of why this brutal organization must be annihilated.”

The destruction of two of Mosul's best-known landmarks adds to a long list of world heritage sites the militants have destroyed in Iraq and Syria, including dozens of sites in Mosul and many of Palmyra's famed monuments.