The Riddle Goes as follow :

You need a map to trace your route to find the clue.
Start in the city that hosts the 3rd largest port in Europe, then travel to the center of high fashion with names like Valentino and Gucci. Then go back to where you started to easily travel to the largest castle in the world. From there, head west for the world’s most famous hotdogs, go back to the largest castle in the world, then head down to the world’s oldest carousel.

A number Must be the Result

Is this a riddle or Geography Homework?

A map and a search engine like Google or Bing would help you find the answer. 'Search' for the clues in your in riddle, mark them on your map, and enjoy learning more about the places you have discovered. Once you have finished your 'travels' look at your map.