Rebels seized control of the Umayyad Mosque in Syria's second city of Aleppo on Thursday after days of fierce clashes that damaged the historic building, a watchdog reported.
Regime troops were forced to withdraw at dawn, taking up positions in buildings around the landmark structure, said the Syrian Observatory for Human Rights.
The mosque's museum caught fire during the battle, causing its ceiling to collapse, adding to damage done in October when antique furnishings and one of its intricately sculpted colonnades were charred in clashes.
The site has been a place of Muslim worship since the 8th century, but the original building was razed by the Mongols in the 13th century, from when the current structure dates.
Elsewhere in Aleppo's UNESCO-listed Old City on Thursday, fighting raged around the Justice Palace and in Sabaa Baharat Square.
Observatory director Rami Abdel Rahman said that if the rebels gain control of the palace, they would be able to cut off army reinforcements to Aleppo's citadel.
The fortress, which in ancient times could shelter a garrison of 10,000 men, is currently held by troops loyal to President Bashar al-Assad.
Rebel fighters who are trying to encircle it claim the army has only one supply route left.
While rebels have taken over large swathes of territory and a number of key military garrisons in the northern province of Aleppo, fighting in the city has been at a stalemate for months.
The Observatory, which gathers its information from a vast network of activists, medics and lawyers, gave a death toll of 157, including 63 civilians, in violence across Syria on Wednesday.
Twelve civilians from a Damascus district, including four members of the same family, were killed under torture in prison after their arrest, according to the Observatory.
It said families received the identity cards of the victims from the security forces on Wednesday night.
The men were all from Nahr Aisha district in the embattled south of the capital, which has seen regular raids and arrests by government troops that have resulted in the imprisonment, torture and killing of other residents, it said.
The Local Coordination Committees, a network of opposition activists on the ground, also reported the deaths and identified the men by name.
Human Rights Watch last week demanded unfettered access to Syrian prisons after a prominent peace activist died in custody and another was feared dead.