1) The world's first stock exchange was established in Amsterdam in 1602.

2) The word "chocolate" contains four vowels: O, O, A, and E.

3) The world's oldest university, Al-Qarawiyyin, was founded in 859 AD and is located in Fez, Morocco.

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.