The legendary Danube River is Europe's second longest river, and runs across Central and Eastern Europe. Flowing through Bulgaria, Germany, Austria, Hungary, Romania, Serbia, Croatia, Slovakia and Ukraine, the Danube has been a major historical setting throughout European history, as well as a main source of trade and travel between the ancient Kingdoms. * The dramatic-looking Hungarian Parliament Building is the seat of the National Assembly of Hungary, but could easily blend in any Lord of the Rings movie.