The criminal mastermind Moriarty is described as the epitome of evil and the only villain that was an intellectual match for Holmes. He is so ingrained in the Sherlock Holmes canon that it is incredible to consider he was instrumental in only one short story, The Final Problem. Tired of what he considered less important writing, Conan Doyle wanted to kill off his hero and created the ultimate nemesis to accomplish this feat. In the climax of The Final Problem, both Holmes and Moriarty plunge "to their deaths" down the Reichenbach Falls in Switzerland. However public pressure forced Conan Doyle to resurrect Holmes in future stories, explaining that he had survived the fall and faked his death while he dealt with Moriarty's henchmen. He did not resurrect Moriarty, feeling that it would diminish Holmes' capabilities if his opponent kept escaping and returning.
If imitation is the sincerest form of flattery, Sir Arthur Conan Doyle should consider himself extremely flattered. Detective Sexton Blake was just one example of shameless ripoffs on the Holmes character. There were also numerous spoof books that spanned all genres, such as "The Sexual Adventures of Sherlock Holmes", "Sherlock Holmes vs Jack the Ripper", "Sherlock Holmes Through Time and Space, Einstein and Sherlock Holmes, and a few ethnic variations including an Indian novel called "Holmes of the Raj" and Japanese graphic novels.
With respect to the author himself, there were several displays devoted to personal artifacts of Conan Doyle, including a handwritten note where he brags about his golf score, as well as photos and notes depicting his belief in spiritualism. His second wife was a medium and would hold seances to try to contact Doyle's oldest son who died of pneumonia towards the end of WWI. There were examples of "spirit writing" where spirits would convey messages to the living by guiding the hand that held the pen. One photo of Holmes and his wife shows a bright glowing light behind them, similar to what would appear if a camera flash reflected in a pane of glass. They believed this to be a spirit photo.
This was an insightful exhibit that encourages you to run out and borrow the tomes of Sherlock Holmes from your nearest public library.