What's it like to be in Syria right now? Frederik Pleitgen has just returned from Damascus and will answer your questions on Facebook at 11 a.m. New York / 4 p.m. London on Thursday.

Damascus, Syria (CNN) The walls of the National Museum of Damascus are stripped bare, brown squares and rectangles standing in for the priceless paintings that once hung here.

The halls of the gallery are empty, as are the glass cases, an occasional placard the only reminder of the treasures that once sat on these shelves.

In the tree-lined garden outside, ancient sarcophaguses rest on their plinths, shielded by concrete shells to protect them from a mortar attack that could seemingly come any moment.

A short walk across the courtyard leads to another building. Standing inside, holding a 4,000-year-old Mesopotamian vase in his hands, Maamoun Abdulkarim offers up a glum assessment of his current job.

"I am the saddest Director-General in the world," he says.

Abdulkarim is Syria's Director-General of Antiquities and Museums. He oversees a gigantic logistical operation to evacuate artifacts from areas of fighting, or places in danger of being seized by ISIS, and bring them to secret and safe locations.

ISIS has taken over large parts of Syria in the past two years, blowing up ancient archaeological sites and destroying priceless antiquities -- anything that conflicts with their brutal and warped view of Islam.

When the country's civil war encroached on Damascus in recent years, Abdulkarim ordered the evacuation of every last artifact from the National Museum.

The work is difficult and it comes at a great cost. On Tuesday ISIS murdered an antiquities expert in the ancient city of Palmyra, one of Syria's most spectacular archaeological sites.

Kalid al-Asa'ad, a university professor and the former general manager for antiquities and museums in Palmyra, was beheaded in the city's public square as militants watched, according to the Syrian Observatory for Human Rights.

On the day our team met Abdulkarim in Damascus last week, the deputy director of the laboratory had just been killed by a mortar round that landed in the gardens outside the national museum.

Damage that will last forever

As depressing as it is to see the National Museum of Damascus stand empty, the alternative could be much worse.

In the past four years, chunks of the Syria's rich cultural heritage have been broken, bulldozed and looted by militias and terror groups.

"Each day I receive new bad messages from the destruction of the cultural heritage in Syria," he says.

But Abdulkarim has vowed to save as much of Syria's heritage as he can -- and he has an army of highly motivated volunteers to help him do the job.

"Finally, the crisis will finish. We are sure," he says. "But the damage to the cultural heritage will be there for all times."

"That's why we are trying to push all Syrians to do the best work to save this cultural heritage. If not, we will be condemned by our children in the future."

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In a courtyard inside the museum compound, dozens of volunteers are busy day-in and day-out cataloguing, photographing and packaging ancient vases, busts, and many other items to protect them until the storm of Syria's war has passed.

"From Deir Ezzor alone we have evacuated about 35,000 pieces," Abdulkarim says. Pointing at another vase, he says, "We saved also thousands of objects like this from Syrian Mesopotamian sites. This is from 2,000 BC."

One of team's greatest accomplishments was the evacuation of almost all of the ancient busts and statues from the Roman ruins of Palmyra, one of Syria's most famous archaeological treasures, just days before ISIS overran the area earlier this year.

In a room at the compound, dozens of Roman statues lay on the floor. This specific batch was retrieved from Lebanon after being looted from Palmyra. But Abdulkarim and his team saved many more from advancing ISIS forces.

"We saved about 4,000 statues and busts," he says. "Just imagine if these objects were now in the hands of ISIS. I am sure they would destroy all of these things."

A deadly race against time

If the work Abdulkarim's team does is difficult, it also represents a rare example of a truly national effort, in a country whose social fabric has been all but torn apart by four years of civil war.

"We have 2,500 people in our directorate general of antiquities. We are a government agency, but we also work in the areas under the control of the opposition," he explains.

Abdulkarim says that almost all of the groups warring with each other in Syria -- aside from ISIS and the Al Qaeda-backed Jabhat al-Nusra -- are united in their support of the work his department is doing.

Photos: The race to save Syria's antiquities Photos: The race to save Syria's antiquities Maamoun Abdulkarim, Syria's Director-General of Antiquities and Museums, holds an ancient vase retrieved from the northeast city of Deir Ezzor. Hide Caption 1 of 10 Photos: The race to save Syria's antiquities Abdulkarim leads a team trying to prevent Syria's cultural heritage from being destroyed. Earlier this year they managed to rescue hundreds of Roman busts from Palmyra before ISIS seized the ancient city. Hide Caption 2 of 10 Photos: The race to save Syria's antiquities Abdulkarim's team evacuated every artifact from the National Museum of Damascus as the war closed in on the capital several years ago. Hide Caption 3 of 10 Photos: The race to save Syria's antiquities In the courtyard of the museum, concrete covers have been constructed around ancient sculptures to protect them from shelling. Hide Caption 4 of 10 Photos: The race to save Syria's antiquities Not all of the sarcophagi have been covered in concrete yet, and the garden has been hit several times by mortar rounds in recent years. Hide Caption 5 of 10 Photos: The race to save Syria's antiquities At a building inside the museum compound, dozens of volunteers catalog the tens of thousands of artifacts that Abdulkarim's team has managed to evacuate from various places in Syria. Hide Caption 6 of 10 Photos: The race to save Syria's antiquities This Roman statue was rescued from Palmyra ahead of ISIS' advance earlier this year. Hide Caption 7 of 10 Photos: The race to save Syria's antiquities The team evacuated 35,000 artifacts from Deir Ezzor alone. Each one is photographed and given a catalog number. Hide Caption 8 of 10 Photos: The race to save Syria's antiquities This fragment dates back to around 2,000 BC during the Mesopotamian era. Hide Caption 9 of 10 Photos: The race to save Syria's antiquities After being photographed and numbered, these priceless artifacts are shipped away to secret and safe locations across the country. Hide Caption 10 of 10

"Our job is scientific, it is professional, it is for all Syrians," he says. "We don't have two cultural heritages, one for the government and one for the opposition army or the political opposition. We have one cultural heritage for all Syrians, for humanity."

Abdulkarim prides himself on leading the battle to save Syria's cultural treasures not only from his office, but on the frontlines. He's travelled to places like the embattled town of Hasakah, to Kurdish territories and, most recently, to Palmyra to oversee the evacuation of the Roman statues and other artifacts.

"It is not easy to work here in this crisis but we don't have any option," he says.

Syria's history is rich and diverse. In addition to ancient cities, the country boasts within its borders some of the oldest churches in the world, dating from the beginnings of Christianity, and important shrines from the earliest times of Islam.

Time is a luxury Abdulkarim and his staff do not have as they race to beat ISIS militants to the country's remaining cultural artifacts. But it is a race they are determined to win. And the team is already preparing for the day when they can bring the treasures they've saved out of their hiding places and put them back on display, where they belong.