The ancient citadel of Aleppo, scarred by Syria's 11-year conflict, suffered further damage in the earthquake that ravaged southern Turkey and northern Syria, a local architect and the Syrian antiquities directorate said.
On Tuesday a pile of rubble near the citadel was all that was left of a structure identified by local architect Mohammed al-Rifaei as the "sheep tower", which he said had stood there until the devastating early morning quake.
"We had repeatedly asked for the restoration of the tower, but now it needs to be rebuilt from scratch," Rifaei said.
Syria's Directorate General of Antiquities and Museums said parts of the citadel had suffered minor to moderate damage.
Parts of an Ottoman-era mill had collapsed, walls had cracked and some of the dome of a mosque's minaret had fallen off.
The towering citadel, listed by the U.N. cultural agency UNESCO as a world heritage site, was significantly damaged in a long-running battle between government and rebel forces before it was reopened in 2018.
UNESCO said on Tuesday "significant damage" had been noted in the citadel. "The western tower of the old city has collapsed and several buildings in the souks have been weakened," it said.
It said several buildings in the Turkish city of Diyarbakir, an important centre in the Roman, Byzantine and Ottoman periods, had also collapsed.
Other ancient sites in Turkey close to the epicentre of Monday's quake include the 2,000-year-old mausoleum at Mount Nemrut and the neolithic ruins of Gobekli Tepe, UNESCO said.
"UNESCO is mobilising its experts, in conjunction with its partners such as ICOMOS, to establish a precise inventory of the damage with the aim of rapidly securing and stabilising these sites," it said in a statement.
Footage broadcast by CNNTurk on Monday showed the historic Gaziantep Castle was severely damaged.
(Reporting by Firas Makdesi; Writing by Dominic Evans; Editing by Ben Dangerfield)