1) The Federal Reserve System, often referred to as the Fed, is the central banking system of the United States.

2) In Aztec mythology, Quetzalcoatl is a prominent deity often depicted as a feathered serpent. He is associated with creation, fertility, and wind, and is considered a cultural hero and patron of priests and rulers. The arrival of Spanish conquistadors was interpreted by some as the return of Quetzalcoatl.

3) The ancient city of Rome was founded in 753 BC and went on to become one of the most powerful and influential civilizations in history.

4) The Danube River, flowing through ten countries in Central and Eastern Europe, is the second-longest river in Europe. It has played a significant role in the cultural and economic development of the regions it traverses and is a popular waterway for river cruises.