What is the name of the waterfall where Sherlock Holmes and Professor Moriarty fought?

Sherlock Holmes and Professor Moriarty fought at Reichenbach Falls.

The confrontation occurs in Arthur Conan Doyle’s short story “The Final Problem,” where Holmes follows Moriarty to Switzerland. At the upper Great Reichenbach Fall, the two enemies struggle beside the gorge, and both are apparently swept to their deaths. Watson arrives too late to witness the fight, finding only signs of the encounter and Holmes’s farewell message.

Reichenbach Falls is a real waterfall in the Bernese Oberland of Switzerland, near Meiringen. The falls descend through several drops, with a total height commonly given as about 250 metres. Doyle had visited the area and used its dramatic landscape as the setting for Holmes’s apparent final case.

The event was not permanent: Doyle later brought Holmes back in “The Adventure of the Empty House.” The waterfall remains closely associated with the detective, and a memorial plaque and Sherlock Holmes museum in nearby Meiringen commemorate the fictional episode.