When the tallest viaduct in the world - the Millau Viaduct in South France - was opened, there was talk of it being in the TdF this year. I can't find it on the route at all.
While I can understand the authorities
not wanting to disrupt holiday traffic for a bike race by closing it, it would have been interesting to watch. Cycling in the clouds ...
Of course it
could also have been closed for weather too, in which case the ASO would have an interesting problem on their hands come the day of that stage.