PALMYRA - Syria's ancient city of Palmyra, which government forces are again battling to retake from jihadists, has become a symbol of the Islamic State group's wanton destruction of cultural heritage.
The city and its ruins, designated a UNESCO world heritage site in 1980, have traded hands several times during Syria's civil war.
IS first seized Palmyra in May 2015 and began to systematically destroy and loot the site's monuments and temples. IS fighters were driven out in March 2016 but recaptured the town last December.
The latest offensive to retake the city saw government forces break through its western limits late Wednesday, but their advance has been slowed by landmines laid by retreating jihadists.
Before the Syrian conflict erupted in 2011, the city of 1,000 columns and a formidable necropolis of more than 500 tombs attracted more than 150,000 tourists a year.
- Ancient trade hub -
Although the precise date of its founding is unknown, Palmyra's name is referred to on a tablet dating from the 19th century BC as a stopping point for caravans between the Mediterranean and the east.
It was during the Roman Empire -- beginning in the first century BC and lasting 400 years -- that the oasis city rose to prominence.
Despite being surrounded by desert, Palmyra developed into a wealthy metropolis thanks to trade in spices, perfumes, silk and ivory from the east.
Known to Syrians as the "Pearl of the Desert", Palmyra boasted temples, colonnaded alleys and elaborately decorated tombs that were some of the best preserved classical monuments in the Middle East.
Some 210 kilometres (130 miles) northeast of Damascus, its name means City of Palms. It is also known by the Arabic name Tadmor, or City of Dates.
The city's temples were built after it was declared a free city by Roman emperor Hadrian in 129 AD, which allowed it to collect its own taxes.
In the third century, Palmyrenes beat back the Romans in the west and Persian forces in the east in a revolt led by Zenobia, who became queen after her husband died in mysterious circumstances.
By 270 AD, Zenobia had conquered all of Syria and parts of Egypt. Her forces advanced into what is now Turkey before they were defeated by the Roman emperor Aurelian near Antakya.
- Campaign of destruction -
IS, which considers statues of humans or animals as blasphemous, overran Palmyra on May 21, 2015.
Three months later, the jihadists beheaded Palmyra's 82-year-old former antiquities chief Khaled al-Assaad and launched a campaign of destruction against treasured monuments.
They destroyed the ancient shrine of Baal Shamin, attacked the 2,000-year-old Temple of Bel and blew up the Arch of Triumph, which dated from around 200 AD.
They also destroyed a dozen of Palmyra's best preserved tower tombs and the famed Lion of Al-Lat outside the city's museum.
The jihadists even used the city's ancient amphitheatre as a venue for public execution-style killings.
Syrian government forces, backed by Russian warplanes, recaptured the city on March 27, 2016, but IS fighters stormed back in on December 11.
In early January, IS launched a new demolition operation, destroying Palmyra's tetrapylon monument and the facade of the city's Roman amphitheatre.