(Reuters) - The Syrian army turned its forces on Aleppo on Wednesday, ordering an armoured column to advance on the country's second biggest city and pounding rebels there with artillery and attack helicopters, opposition activists said.
- Helicopters fired missiles throughout Tuesday, residents said. Rebels were battling government forces by the gates of the historic old city. Troops fired mortars and shells at rebels armed with rifles and machineguns.
- The ancient Silk Road city, with its leafy streets and faded, old-world hotels, had been spared serious violence until February, when pro-Assad shabbiha militia killed at least 10 people at a pro-democracy demonstration.
- It is in the northwest part of Syria, about 30 miles (50 km) south of the Turkish border. Aleppo is at the crossroads of historic commercial routes, some 60 miles (100 km) from the Mediterranean Sea to the west and the Euphrates River on the east.
- Aleppo dates from the early second millennium BC. It became a centre of Muslim resistance to the Crusaders, who besieged it unsuccessfully in the 12th century.
- In 1260 Aleppo was taken by the Mongols, who massacred its inhabitants. After several centuries under the Mamluks, the city was in 1516 incorporated into the Ottoman Empire and underwent a remarkable commercial growth, becoming the principal market in the Levant.
- In the 20th century the city became an industrial centre to rival the capital Damascus. The commercial hub is now home to more than 2.5 million people, dominated by Sunni Muslims and with a minority population of Christians.
- The ancient city is on UNESCO's World Heritage list. Architectural gems - bathhouses, madrassa schools, palaces, churches and mosques - mark Aleppo's streets.
- The monumental Citadel of Aleppo is testament to Arab military might from the 12th to the 14th centuries. It contains the remains of mosques, palace and bath buildings.
- Earlier this year, UNESCO alerted the Syrian authorities to their responsibility to ensure the protection of the country's cultural heritage.
Reporting by David Cutler, London Editorial Reference Unit