Laufen Castle sits directly on the clifftop above the Swiss bank of the Rhine Falls, its foundations going back to the 12th century. The combination of medieval fortification and the waterfall crashing below is one of the better natural viewpoints in Switzerland — there is a paid viewing platform cut into the cliff that puts you very close to the water, close enough to feel the spray. The platform descends via a lift carved into the rock face.
The castle now houses a restaurant and small museum about the falls and the region's history. The restaurant is functional rather than memorable, but the terrace tables above the gorge are worth booking in summer. If you are coming specifically for the falls, Laufen gives you the elevated perspective while the boat trips from the base give you the immersive one — ideally do both.