A landlocked country of central Europe. Settled by Celtic tribes, the region was conquered (15 B.C.-A.D. 10) by the Romans and later (8th century) by Charlemagne, who made it a border state of the Carolingian Empire. In the 13th century, Austria passed to the Hapsburg family and remained the core of their vast holdings until the dissolution of Austria-Hungary in 1918, when Austria became a republic. Annexed by Adolf Hitler in 1938, Austria regained full sovereignty in 1955. Vienna is the capital and the largest city. Population: 8,200,000.