This is probably one of the strangest place you will be able to visit on the Riviera.
This village is completely abandoned. There still are important ruins, though, invaded by vegetation. A castle tower with its cells, the city walls and the ruins of the houses. You will be able to wander among them and enjoy the wide sightseeings offered on the vicinities: Mt Chauve on the West, Alps North and Nice South.
You can freely access the ruins. Of course, to walk there is not without danger. Beware the stones which might fall, the uneven ground...
The feeling is surprising. This is not Pompeï of course but you really are in the streets of a village abandoned by its inhabitants after it was sacked by the Revolution army at the end of the 18th century. (It was then italian.) The village was rebuilt a little lower, where it still stands. That's also the place where the original village, built by the Romans, stood. It had been moved a first time uphill, to avoid the sacks by Lombards and Arabs in the high Middle Age, and simply retrurned to its very first site.
To go to the ruins from Nice take the direction of Levens, and then turn right towards Contes. Park your car at the pass, at the highest point of the road. From there, on the right there is a road which is usually closed. Walk along this road and 15mn later you'll be in the ruins, on your left. If this road is open go on with your car and park at the foot of the ruins.
To go to the Chateauneuf village continue on the road beyond the pass and descend towards Contes. The village has no particular interest.