I went to Kassel to see the Documenta exhibition this summer, and was looking for a hotel not too far from the museum spaces. Hotel Kurfürst Wilhelm I is located next to the railway station, a ten minute tramride away from the city center. The tram leaves every five minutes. The hotel gave us a free travelcard, and a friendly hotelworker was very good at providing information about trams, buses and maps.

But: If you want to be located in the city center, chose another hotel. The area around the railway station has no interest, no restaurants, no museums, no nice shops.
Also, the hotel is very simple, the room was ok and clean, but had no bathtub, only a simple shower, and we had a hard time finding the lightswitches. The breakfast buffet was ok, but nothing special.
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