Evidence of continuous habitation has been found since 500 BC, when the site of Vienna on the Danube River was settled by the Celts. In 15 BC, the Romans fortified the frontier city they called Vindobona to guard the empire against Germanic tribes to the north.
Close ties with other Celtic peoples continued through the ages. The Irish monk Saint Colman (or Koloman, Irish Colmán, derived from colm "dove") is buried in Melk Abbey and Saint Fergil (Virgil the Geometer) was Bishop of Salzburg for forty years, and twelfth century monastic settlements were founded by Irish Benedictines. Evidence of these ties are still evident in Vienna's great Schottenstift monastery, once home to many Irish monks.
During the Middle Ages, Vienna was home to the Babenberg dynasty; in 1440, it became the resident city of the Habsburg dynasties. It eventually grew to become the de facto capital of the Holy Roman Empire (1483/1806) and a cultural centre for arts and science, music and fine cuisine. Hungary occupied the city between 1485–1490.
In the 16th and 17th centuries, the Ottoman armies were stopped twice outside Vienna (see Siege of Vienna, 1529 and Battle of Vienna, 1683). A plague epidemic ravaged Vienna in 1679, killing nearly a third of its population.
In 1804, during the Napoleonic wars, Vienna became the capital of the Austrian Empire and continued to play a major role in European and world politics, including hosting the 1814 Congress of Vienna. After the Austro-Hungarian Compromise of 1867, Vienna remained the capital of what was then the Austro-Hungarian Empire. The city was a centre of classical music, for which the title of the First Viennese School is sometimes applied.
During the latter half of the 19th century, the city developed what had previously been the bastions and glacis into the Ringstraße, a new boulevard surrounding the historical town and a major prestige project. Former suburbs were