For a great view of the city (especially at night) go to the top of the Eiffel Tower at Paris. It also offers a great vantage point for viewing the water show at the Bellagio.
Make sure you try currywurst in Germany. It's basically a hot dog with tomato sauce (ketchup) and curry powder. Tastes brilliant and only costs 1 or 2 Euro.
Definitely worth doing if you are in any way interested in Ancient Rome - the guide is a wealth of knowledge.