As the world's third largest Gothic-style cathedral and a UNESCO World Heritage Site, the Cologne Cathedral is a must-see.
If you can't get enough of German Castles, check out Schloss Drachenburg. You can grab a drink at the top and enjoy the views of the Rhine river valley.
Haribo originates in Bonn - visit their flagship store in the city centre for a wide range of sweets and souvenirs, including a pick and mix station.
Visit the Lindt Chocolate Museum on the banks of the Rhine in Cologne to learn about the 5000-year cultural history of cocoa and modern chocolate production, and try a sample from the chocolate fountain at the heart of the museum.