So here they are, wonderful sites, artefacts, and museums.
The Laténium in Neuchâtel is a very modern and didactically well presented museum. With many replicas and play-around-thingies it is not a museum I am normally looking forward to visit, but it was absolutely worth seeing. The best object was the little venus figurine from the Upper Palaeolithic site of Monruz. It is made of black jet and only 1.6 cm high with a hole drilled in, so it was maybe used as a pendant.
We didn't see a megalithic tomb, however the megalithic alignement in Clendy, Yverdons-les-Bains was impressive, too:
Bone pendants, typical for the late Cortaillod (Middle Neolithic) culture, found in a lacustrine village near Yverdon-les-Bains: