Varna is seaport and third largest city in Bulgaria. It is situated on nearly 29 sq. km and its population is 335 000. Lying on the north shore of Varna Bay on the Black Sea coast, the city is sheltered by the Dobrudzhansko plateau, which rises to more than 1,000 feet (300 m) above sea level. A narrow canal (1907) links Varna Lake, a drowned valley into which the Provadiyska River flows to the Black Sea. The city is an important administrative, economic, cultural, and resort centre. It is a modern city, with wide, tree-lined boulevards, a fine park on the waterfront, and spacious beaches. Along the coast north of Varna are several popular resort towns, including Druzhba, Zlatni Pyassutsi («Golden Sands»), Albena, and Balchik, the last once the summer retreat of Romanian royalty and aristocracy. Varna was founded as Odessus by Milesian Greeks in the 6th century BC; later it was Thracian and Roman. In AD 681 it became part of the First Bulgarian empire (c. 679-1018) and was named Varna. During the reign (1218) of Ivan Asen II, it became a thriving centre of trade with Genoa, Venice, and Dubrovnik. After falling under Ottoman domination in 1391, it continued to grow in importance. In 1444, in a pitched battle fought nearby, the Turkish armies of Murad II routed the armies of the last Christian Crusade against the Turks in the Balkans. The Russians captured Varna in 1828 during the war for the liberation of Greece, but, when they left, the city reverted to the Turks. In 1854 Varna became a base for Anglo-French troops operating against Sevastopol during the Crimean War. It was liberated from the Turks in 1878 and ceded to Bulgaria by the Treaty of Berlin. After the building of the Ruse-Varna railway in 1866 and the rail link to Sofia in 1899, the town expanded further. A modern harbour was constructed in 1906. The city has regular domestic airline services and, in the summer, international flights. Regular boat and bus services connect the Black Sea towns. Much of Bulgaria's maritime and river transport passes through Varna's harbour, which accommodates vessels up to 20,000 tons. Major export items are livestock, grain, and processed foodstuffs. Industries include flour milling, boatbuilding, and manufacturing. Varna is one of the most dynamically developing Bulgarian cities with good road communications, well organized air, sea and railway transport. There is a ferryboat line Varna - Ilichovsk, Ro-Ro lines Varna - Ilichovsk and Varna - Poti. Varna is the third biggest industrial center in the country with busy shipping, shipbuilding and ship-repair activities. Varna hosts some prestigious cultural events: the Varna Summer International Music Festival, the International Ballet Competition, the International Print Biennale, the Prof. G. Dimitrov International Choral Competition, the Love is Folly International Film Festival, the Golden Rose Festival of Bulgarian Feature Film, the Golden Dolphin Festival of Puppet Art. The city has several universities, a naval academy, an oceanography and fishery-research institute, a medical school, museums, a theatre, an opera house, and art galleries. The 4th-century Aladzha Monastery, one of the earliest Bulgarian monasteries, overlooks the city from the north; its cells and chapel are carved out of the rock. A 5th/6th-century basilica is a reminder of an ancient Genoese colony.