On clear days from the Vosges mountains you can easily see the French Alps (and even part of Austrian Alps if lucky), and especially the Mont Blanc. e.g places

On clear days from the Vosges mountains you can easily see the French Alps (and even part of Austrian Alps if lucky), and especially the Mont Blanc. e.g places like the Ballon D'Alsace, and even all the way up north to Donon or Nideck+Schneeberg†. Quite a bit shorter in distance (between 200 and 300km depending on where you sit) but visually stunning. I seem to recall in older times there used to be some light semaphore infrastructure to communicate over these distances. https://web.archive.org/web/20251008080738mp_/https://i72.servimg.com/u/f72/12/92/78/27/pict0016.jpg https://web.archive.org/web/20251008080738mp_/https://i72.se... https://www.vosgesmatin.fr/environnement/2023/12/19/quand-le-mont-blanc-se-dessine-au-loin-depuis-le-ballon-d-alsace https://www.vosgesmatin.fr/environnement/2023/12/19/quand-le... https://www.vosgesmatin.fr/environnement/2022/11/12/quand-le-mont-blanc-se-decouvre-depuis-le-ballon-d-alsace https://www.vosgesmatin.fr/environnement/2022/11/12/quand-le... † Which I hiked this year, unfortunately only had a phone so all I get is the memory of seeing the Mont Blanc from there.