The U.N. training and research agency released satellite images and analysis that confirmed the Temple of Bel -- which for nearly 2,000 years has been the center of religious life in Palmyra, Syria -- was no longer standing, despite conflicting reports earlier in the day that it was not fully demolished.
UNOSAT Manager Einar Bjorgo said he could "confirm destruction of the main building of the Temple of Bel as well as a row of columns in its immediate vicinity."
Syria's antiquities chief, Maamoun Abdulkarim, said earlier on Monday that the temple's iconic columns were still standing, despite an explosion there Sunday.
He said there was an explosion Sunday inside the walls of the Temple of Bel, and while the extent of the damage was not yet known at the time, witnesses reported the walls were still standing. He called the site "the most important temple in Syria
and one of the most important in the whole Middle East."
The UK-based Syrian Observatory for Human Rights reports had reported previously that the temple had been at least in part damaged by ISIS.
ISIS has become known not only for its brutal executions but also for its hatred of antiquities and its wanton destruction of them.
Recently, it executed Khaled al-As'ad, an 82-year-old man who had spent his life on the painstaking task of preserving antiquities in Palmyra, because he refused to reveal where various irreplaceable relics had been hidden.
'Meeting point' between classical, Eastern architecture
The first-century temple, which is dedicated to the ancient "god of gods," is one of the largest and best-preserved in the region and represents a meeting point between classical and Eastern architecture, Abdulkarim said.
ISIS, perhaps the most brutal terrorist group to emerge in modern times, has shown a taste for demolishing irreplaceable ancient sites and antiquities. It considers "pre-Islamic religious objects or structures sacrilegious," wrote Sturt Manning
, chairman of Cornell University's Department of Classics, in an opinion piece for CNN.com.
"It seeks to destroy diversity and enforce narrow uniformity. Evidence of a tolerant, diverse past is anathema," he said. "What it fears is memory and knowledge, which it cannot destroy."
Last week, ISIS published photos of its destruction of the temple of Baal Shamin, the first major structure in the ancient city of Palmyra to be destroyed.