WMG / The Tripods

The (fictional) castle at Reichenbach Falls in Sherlock Holmes: A Game of Shadows later becomes humanity's base in The Tripods

It's in Switzerland, and up in the mountains, good water supply. It matches the base in The White Mountains. Interestingly, Sherlock and Watson follow the story fairly closely - the two start in England, they go to France and pick up a third member, then end the story in the White Mountains.