Something that has recently struck me as interesting was the location of 221B Baker Street. Why did Doyle decide to place his protagonists in this particular place? An important thing to point out at this point, is that there is no real 221B Baker Street.

Harley Street is a street in Marylebone, London, England. Since the nineteenth century, it has been known for its large umber of doctors, hospitals and medical organizations. 

Grovesnor Place is a street in Belgravia, London, England. 

Devonshire Place is a street in the City of Westminster, London, England. The London Clinic, one of England's largest hospitals, is located at the north of the street.  Multiple literary figures have lived on the street, such as Matthew Lewis, author of gothic novel The Monk: A Romance, who once lived at No. 9. 

Cheltenham is a spa town on the edge of the Cotswolds in Gloucestershire, England. It has been a spa town since the discovery of mineral springs in 1716, and claims to be the most complete Regency town in England with many listed buildings.