This article originally appeared on VICE News.The Grand Mosque of al-Nuri, one of Islam's great cultural and religious monuments, was destroyed Wednesday in the battle for Mosul.Iraqi forces say the Islamic State destroyed the 12th century building, while ISIS blames airstrikes by US-led coalition forces. Aerial images back up the Iraqi forces' version.The mosque was the site where ISIS leader Abu Bakr al-Baghdadi in 2014 declared a self-styled caliphate for the militant group spanning parts of Syria and Iraq.VICE News spoke to historian Dan Cruickshank about this latest act of cultural vandalism and the significance of what's been lost.