In Sherlock Holmes stories, what is the detective's street address in London?

Sherlock Holmes's London address is 221B Baker Street.

The address appears throughout Arthur Conan Doyle's stories as the home Holmes shares with Dr. John Watson. Baker Street is a real thoroughfare in the Marylebone district of London, but the exact number 221B was fictional when Doyle wrote the earliest stories. The letter B distinguishes the lodging from number 221.

Holmes and Watson's rooms are presented as a working domestic space and investigative headquarters. Visitors bring cases there, Watson writes accounts of their adventures, and Mrs. Hudson is described as their landlady. The address therefore became as closely associated with Holmes as his deerstalker, pipe, and magnifying glass.

A common mix-up is assuming that the famous address was always a real location. When the stories were published, Baker Street did not have a 221B in the modern sense. The Sherlock Holmes Museum now uses 221B Baker Street as its official address, commemorating the fictional residence.