For 10 points, name this second longest river of Europe that starts in the Black Forest of Germany and flows into the Black Sea.
The Statue of Decebalus is located on the banks of this river nearby an ancient structure called the Tabula Traiana, which is the primary ruin left from a bridge believed to be the longest arch bridge for a millenium. The primary sources of this river are the Brigach and Berg Rivers. Tributaries of this river include the Drava River in Croatia and the Tisza River in Serbia. A notable gorge on this river is called the Iron Gates. This river flows through the capital cities of Belgrade, Bratislava, Budapest, and Vienna. For 10 points, name this second longest river of Europe that starts in the Black Forest of Germany and flows into the Black Sea.
The Statue of Decebalus is located on the banks of this river nearby an ancient structure called the Tabula Traiana, which is the primary ruin left from a bridge believed to be the longest arch bridge for a millenium.
Danube River