Damascus, the world's oldest continually inhabited city, is now a key battleground in Syria's civil war, which enters its third year in March.

Rebel forces are intensifying their assault on the ancient capital, where the beleaguered minority regime of President Bashar Assad has concentrated its elite and most loyal troops.

The other flash point is in the north around Aleppo, another ancient city that used to be Syria's commercial heart, with rebel forces steadily making gains in heavy fighting.

But the war, which the United Nations estimates has killed 70,000 people since the uprising against Assad began March 15, 2011, is likely to be won or lost in Damascus. And there's probably hard fighting still ahead.

Government forces hold the center of Damascus and a ring of strong points that have blocked major rebel efforts to break into the inner city where the regime's military and intelligence power centers are located.

Fighting has raged for months and the rebels, mainly the ferocious jihadist groups and the secular Free Syria Army, are able to sometimes penetrate this ring of steel and concrete with devastating effect.

On Feb. 21, a huge car bomb exploded outside the headquarters of the ruling Baath Party, a prominent symbol of the regime on Thawra Street in the downtown district of Maazra.

The state news agency reported 53 people killed and more than 200 wounded. The United Kingdom's Syrian Observatory for Human Rights, a pro-opposition monitoring group, put the death toll at 61.

Including other bombings in the city that day, the Observatory said the fatality toll was 85.

One of the wounded was Nayef Hawatmeh, leader of the Democratic Front for the Liberation of Palestine, a longtime Syrian puppet and a relic of the Palestinian wars of the 1970s and '80s.

The Russian Embassy was damaged in the Thawra Street blast, which occurred as rebel forces made a determined effort to push into the city center.

These forces, largely from Syria's Sunni majority, have been held by regime's superior firepower and control of the air.

The army's elite units are manned by minority Alawites, an obscure offshoot of Shiite Islam which dominates the regime.

As pillars of thick black smoke billowed over the city, army headquarters came under mortar fire. Other mortar rounds exploded near Assad's presidential palace.

Some parts of the old city have been badly hit by the destructive chaos. World heritage sites, including the fabled Umayyad Mosque, built after the Arab conquest of the city in A.D. 634, have been damaged, just as much of the historic vaulted souk, or market, in Aleppo were burned down.

Damascus has seen it all before over the millennia -- and survived.

Carbon dating indicates it has probably been inhabited since 6300 B.C.

It's always been fought over. In 1260 B.C, it became a battlefield between the Hittites from the north and the Egyptians from the south, who emerged victorious. By the eighth century B.C. Damascus was the cultural and economic center of the Near East, and remained so for more than 1,000 years.

It's been conquered many times, by Alexander the Great in 323 B.C., finally by Australian cavalry, as well as Britain's legendary Col. T.E. Lawrence on Oct. 1, 1918, when the Ottoman Empire finally crumbled.

The current conflict seems to have "evolved into a war of attrition," says Middle East analyst Victor Kotsev.

"Despite significant rebel advances in the last few weeks and months -- including the capture of a major air force base in Aleppo and the largest dam in the country -- the conflict has stalemated and right now it looks as if President Assad may be able to cling to power for longer than most Western officials and media outlets acknowledge.

"Still, in the end, he's likely doomed, but not so much because he stands to collapse rapidly in the manner in which Moammar Gadhafi did in 2011.

"Instead, as experts note, regime troops can't easily be replaced, as compared to rebels, who are drawing on a larger pool of willing fighters, from Syria and abroad," Kotsev noted.

So things may be getting pretty bad for Assad. The regime was recently reported to have been forced to recruit women to fill the ranks of the beleaguered army.