Syria has been engulfed in a devastating civil war since 2011 after Syrian President Bashar Assad lost control over large parts of the country to multiple revolutionary groups. The conflict has since drawn in foreign powers and brought misery and death to Syrians.

Syria's army, officially known as the Syrian Arab Army (SAA), is loyal to Syrian President Bashar al-Assad and is fighting to restore the president's rule over the entire country. The SAA has been fighting alongside a number of pro-Assad militias such as the National Defense Force and has cooperated with military advisors from Russia and Iran, which back Assad.

Turkey, which is also part of the US-led coalition against IS, has actively supported rebels opposed to Assad. It has a tense relationship with its American allies over US cooperation with Kurdish fighters, who Ankara says are linked to the Kurdistan Workers' Party (PKK) fighting in Turkey. Turkey has launched multiple military offensives targeting Kurdish militias.

The Kremlin has proven to be a powerful friend to Assad. Russian air power and ground troops officially joined the fight in September 2015 after years of supplying the Syrian army. Moscow has come under fire from the international community for the high number of civilian casualties during its airstrikes. However, Russia's intervention turned the tide in war in favor of Assad.

A US-led coalition of more than 50 countries, including Germany, began targeting IS and other terrorist targets with airstrikes in late 2014. The anti-IS coalition has dealt major setbacks to the militant group. The US has more than a thousand special forces in the country backing the Syrian Democratic Forces.

The Free Syrian Army grew out of protests against the Assad regime that eventually turned violent. Along with other non-jihadist rebel groups, it seeks the ouster of President Assad and democratic elections. After suffering a number of defeats, many of its members defected to hardline militant groups. It garnered some support from the US and Turkey, but its strength has been greatly diminished.

Fighting between Syrian Kurds and Islamists has become its own conflict. The US-led coalition against the "Islamic State" has backed the Syrian Democratic Forces, an alliance of Kurdish and Arab militias. The Kurdish YPG militia is the main component of the SDF. The Kurds have had a tacit understanding with Assad.

"Islamic State" (IS) took advantage of regional chaos to capture vast swathes of territory in Iraq and Syria in 2014. Seeking to establish its own "caliphate," IS has become infamous for its fundamentalist brand of Islam and its mass atrocities. IS is on the brink of defeat after the US and Russia led separate military campaigns against the militant group.

IS is not the only terrorist group that has ravaged Syria. A number of jihadist militant groups are fighting in the conflict, warring against various rebel factions and the Assad regime. One of the main jihadist factions is Hay'at Tahrir al-Sham, which controls most of Idlib province and has ties with al-Qaeda.

Iran has supported Syria, its only Arab ally, for decades. Eager to maintain its ally, Tehran has provided Damascus with strategic assistance, military training and ground troops when the conflict emerged in 2011. The Iran-backed Lebanese Shiite militant group Hezbollah also supports the Assad regime, fighting alongside Iranian forces and paramilitary groups in the country.

The ancient Citadel of Aleppo, which rose to its peak during the 12th and 13th centuries, is one of the oldest fortresses in the world and has been a UNESCO World Heritage Site since 1986. The war destroyed the surroundings and parts of the citadel. In the meantime, however, it can be visited again.

This photo shows the intact surroundings of the celebrated citadel complex — with origins going back to the 3rd millenium BC — before the war. The mosque complex dating from the 13th century, which is located directly in front of the Citadel of Aleppo, was heavily damaged when the Syrian Army used it as a military base.

The Umayyad Mosque of Damascus is one of the oldest mosques in the world, having been built at the beginning of the 8th century. The mosque is located in the historic Old Town, which has been a UNESCO World Heritage Site since 1980.

With more than 1,000 small shops, Aleppo's old bazaar, or souk, was the heart of the storied Syrian city — the largest by population in the country before the civil war began. But the Syrian conflict destroyed much of the old city where the bazaar is located, and large parts of the labyrinthine structure remain devastated today.

The more than 2,000-year-old temple that was consecrated in honor of the Mesopotamian god Bel was a highly preserved ruin in the oasis town of Palmyra before the war. However its central building, the cella, and its sanctuaries were blown up by the so-called Islamic State in 2015.

Since the ancient cultural and trading city of Palmyra became a UNESCO World Cultural Heritage site in 1980, its primary temple became a major archaeological site. The reliefs and architectural elements pictured above are from a temple tomb excavated between 1981 and 1985 in a cooperation between the German Archaeological Institute and the Syrian Directorate of Antiquities.

A photo taken in 2001, when no one suspected the suffering and destruction the city would experience barely a decade later. It shows Aleppo's citadel peacefully overlooking the Old Town bathed in a golden light. At the time, the minaret of the Great Mosque had just been scaffolded for renovation.

Aleppo has become a symbol of Syria's civil war. Large parts of the once flourishing metropolis, Syria's former economic powerhouse, are no longer recognizable. The large Waqf complex of the Abshir Pasha mosque (left), and the Behramiyah mosque (right) in the historic Al-Jdayde district suffered catastrophic damage during the conflict.