Baden was a spa town town located in the Grand Duchy of Baden in the western Germany, near the River Rhine. Its hot springs were renowned across Europe since Roman times, and were rumored to have many healthful, curative properties. By the mid-19th century Baden had become a popular holiday destination for wealthy Europeans from across the continent, including royalty, the nobility, and other celebrities. The town was especially popular with the British and Russians.
Dr John Watson traveled to Baden while investigating the disappearance of Lady Frances Carfax for Sherlock Holmes, an adventure recounted in "The Disappearance of Lady Frances Carfax". After investigating the travel office in Lausanne, Lady Frances' last known address, Watson followed her trail to Baden, where he learned that she stayed at the Englischer Hof for two weeks. There she met the Shlessingers, a missionary couple from South America, who were at the spa for health reasons. When the Shlessingers left to return to London, Lady Frances traveled with them, after which nothing more had been heard from her. Watson also learned that Lady Frances' maid, Marie Devine, had publicly quit her service, and that a "savage" man had been inquiring for her at her hotel, just as in Lausanne.