(CNN) Syrian troops have entered the ancient city of Palmyra and are poised to retake it from ISIS militants, Syrian state media reported Thursday.

State TV broadcast images that purportedly show government forces entering the southwestern part of the city, while a TV anchor said the army is "close to announcing that Tadmur" -- another name for the area around Palmyra's historic ruins -- "has been cleared of ISIS terrorists."

Before-and-after photographs of the destruction. The US and ISIS trade blame for its loss

A 15-year civil war of incredible brutality, successive battles with Israel, and sweeping urban development has robbed the 'Paris of the Middle East' of much of its visual lustre. Once known for its landscape of swaggering Ottoman, French and Art Deco architecture, officials say just 400 of 1200 protected historic buildings remain.

'Old Beirut', Lebanon – A 15-year civil war of incredible brutality, successive battles with Israel, and sweeping urban development has robbed the 'Paris of the Middle East' of much of its visual lustre. Once known for its landscape of swaggering Ottoman, French and Art Deco architecture, officials say just 400 of 1200 protected historic buildings remain.

This 121-year-old wooden building, humble but elegant, was home to the nation's first governor general Muhammed Ali Jinnah for the last phase of his life. The residency was attacked with rocket fire by a separatist group in 2013 , and almost completely demolished. A new structure is being built on the site.

Home to one of the world's most impressive collections, with over 100,000 pieces that cover the entirety of Islamic history. The Cairo site was first built in 1881, the museum recently underwent an eight-year multi-million dollar renovation. Shortly after re-opening, a car bomb targeting a nearby police building caused catastrophic damage and forced the museum to close again.

A key city for the Greeks and Romans, established in 630 BC. Famed as the basis for enduring myths and legends, such as that of the huntress heroine of the same name and bride of Apollo. The ruins were some of the best preserved from that period, but in the wake of Libya's revolution, vast tracts have been bulldozed including its unique necropolis complex.

Memorial site to the 1.5 million killed between 1915 and 1923, the Deir Ez-zor became a yearly destination for pilgrims from around the world. The site included a church, museum, and fire that burned continuously. The complex was destroyed by ISIS in 2014

Among Syria's most famous Ottoman-style mosques, which also shows Mamluk influence through its light and dark contrasts. The vast site became a hub of the battle for Homs, itself a front-line of the conflict. The sacred mausoleum has been completely destroyed and much of the interiors burned.

The purported resting place of biblical prophet Jonah, along with a tooth believed to be from the whale that consumed him. The site dated to the 8th century BC, and was of great importance to Christian and Muslim faiths. It was entirely blown up by ISIS militants in 2014 as part of their campaign against perceived apostasy.

The Crusader castle from the 11th century survived centuries of battles and natural disasters, becoming a World Heritage site in 2006 along with the adjacent castle of Qal'at Salah El-Din. The walls were severely damaged by regime airstrikes and artillery in 2013 , and rebels took positions within it.

Theancient Assyrian city around Nineveh Province, Iraq was home to countless treasures of the empire, including statues, monuments and jewels. Following the 2003 invasion the site has been devastated by looting , with many of the stolen pieces finding homes in museums abroad.

This French-built suspension bridge was a popular pedestrian crossing and vantage point for its views of the Euphrates River. It became a key supply line in a battle for the city, and collapsed under shelling. Deir Ez-zor's Siyasiyeh Bridge was also destroyed.

The covered markets in the Old City are a famous trade center for the region's finest produce, with dedicated sub-souks for fabrics, food, or accessories. The tunnels became the scene of fierce fighting and many of the oldest arenow damaged beyond recognition, which Unesco has

The fortress spans at least four millennia, from the days of Alexander the Great, through Roman, Mongol, and Ottoman rule. The site has barely changed since the 16th century and is one of Syria's most popular World Heritage sites. The citadel has been used as an army base in recent fighting and several of its historic buildings have been destroyed

These 20-meter wide water wheels were first documented in the 5th century, representing an ingenious early irrigation system. Seventeen of the wooden norias (a machine for lifting water into an aqueduct) survived to present day and became Hama's primary tourist attraction, noted for their groaning sounds as they turned. Heritage experts documented several wheels being burned by fighters in 2014.

A world heritage site originally built in 715 by the Umayyad dynasty, ranking it among the oldest mosques in the world. The epic structure evolved through successive eras, gaining its famous minaret in the late 11th century. This was reduced to rubble in the Syrian civil war in 2013, along with serious damage to the walls and courtyard, which historians have described as the worst ever damage to Syrian heritage.

The Great Mosque of Aleppo, Syria – A world heritage site originally built in 715 by the Umayyad dynasty, ranking it among the oldest mosques in the world. The epic structure evolved through successive eras, gaining its famous minaret in the late 11th century. This was reduced to rubble in the Syrian civil war in 2013, along with serious damage to the walls and courtyard, which historians have described as the worst ever damage to Syrian heritage.

Continually inhabited for 2,500 years, and became the capital of the Romans' Arabian empire. The centerpiece is a magnificent Roman theater dating back to the second century that survived intact until the current conflict. Archaeologists have revealed the site is now severely damaged from mortar shelling

Yemen's capital city of Sanaa has seen several suicide bombings for which ISIS claimed responsibility, and air strikes by the Saudi-led coalition -- although it is unclear who is responsible to the latest damage. These have affected both the old fortified city -- inscribed on UNESCO's World Heritage List since 1986 -- and the archaeological site of the pre-Islamic walled city of Baraqish, causing "severe damage," according to UNESCO itself.

The most spectacular legacy of Buddhism in the war-torn country, among the tallest standing Buddhas in the world -- the larger at 53 meters, the other 35 -- had survived over 1,500 years since being carved out of sandstone. The Taliban considered the monuments idolatrous and destroyed them with dynamite

An "oasis in the Syrian desert"according to UNESCO, this Aramaic city has stood since the second millennium BC and featured some of the most advanced architecture of the period. The site subsequently evolved through Greco-Roman and Persian periods, providing unique historic insight into those cultures. ISIS now controls the ancient city and has destroyed shrines, temples and monuments

Once the largest mosques in the world, built in the 9th century on the Tigris River north of Baghdad. The mosque is famous for the Malwiya Tower, a 52-meter minaret with spiraling ramps for worshipers to climb. The site was bombed in 2005 , in an insurgent attack on a NATO position, destroying the top of the minaret and surrounding walls.

By June, the Islamic extremist group began destroying historical sites. The Syrian government said ISIS destroyed two Muslim holy sites: a 500-year-old shrine and a tomb where a descendant of the Prophet Mohammed's cousin was reportedly buried.

Two months later ISIS destroyed more antiquities, including the 1,800-year-old Arch of Triumph that framed the approach to the city and the nearly 2,000-year-old Temple of Baalshamin . ISIS also beheaded the antiquities expert who looked after the ruins.

UNESCO, the U.N. agency that compiles a list of the world's most important cultural and natural sites, called the temple's destruction a war crime.

Palmyra, in the Homs countryside northeast of Damascus, was a caravan oasis when Romans overtook it in the mid-first century. In the centuries that followed, the area "stood at the crossroads of several civilizations" with its art and architecture mixing Greek, Roman and Persian influences, according to UNESCO.

ISIS says it's still in control

After the news that Syrian troops were poised to retake Palmyra, ISIS released a video to prove it still controls the city.

The video shows the city's deserted streets and then cuts to an ISIS militant sitting on a tank, in an indistinctive desert location, saying the group will defeat any forces that try to enter the city. Also in the video is a panoramic shot of Palmyra's ruined historical site, taken from a distance.

CNN cannot independently verify the video's authenticity.

Thursday's reported advance by Syrian troops comes a day after they captured a strategic hilltop on Palmyra's outskirts, according to state media and the Syrian Observatory for Human Rights, a London-based monitoring group.

The observatory said Thursday that Syrian troops were clashing with ISIS fighters while receiving help from Syrian and Russian warplanes. The troops were a few hundred yards from a main southwest entrance into the city, the group said.

The official Syrian Arab News Agency reported Thursday that Syria's army took over three locations west of Palmyra -- al-Qubour Valley, al-Qusour Mountain and al-Tar Mountain -- and that troops "eliminated, to the last one" all ISIS factions in that area.

The agency cited a military source.

The Syrian army "killed or injured all ISIS terrorists at Dedeman Hotel" and at a roundabout near Palmyra's southwestern entrance, according to the same report.

History destroyed

Irina Bokova, of UNESCO, praised the news that Syrian troops had entered the city.

"I welcome the liberation of the Palmyra archeological site, martyr city inscribed on the UNESCO World Heritage List, which carries the memory of the Syrian people, and the values of cultural diversity, tolerance and openness that have made this region a cradle of civilization," she said in a statement.

Among the other ISIS-destroyed historical sites in Palmyra are the Temple of Bel, which dated to 32 A.D.; the 1,900-year-old lion statue that stood at the entrance to the city's museum; and three ancient tower tombs dating as far back as 44 A.D, including the Tower of Elahbel, built in 103 A.D. and regarded as the finest example of this type of building, SANA reported.

"For one year, Palmyra has been a symbol of the cultural cleansing plaguing the Middle East," Bokova said.

"As soon as security conditions allow, UNESCO is ready to go to Palmyra with those responsible for Syrian antiquities on a mission to evaluate damage and protect the priceless heritage of the city of Palmyra, crossroad of cultures since the dawn of humanity," she said. "The deliberate destruction of heritage is a war crime, and UNESCO will do everything in its power to document the damage so that these crimes do not go unpunished."