It’s elementary: On the trail of Sherlock Holmes

>> that of course is tower bridge and london is a city with a rich history that's produced an awful lot of character, none more popular or well known than sherlock holmes . nbc's keith miller went in search of that famed detective.

>> there have been 211 films about him, 75 different actors portraying the famous detective. he is as alive today as he was when he was invented more than 100 years ago.

>> reporter: he's as english as warm beer and double decker busses. sherlock holmes first appeared on the streets of london 125 years ago. and he's still sleuthing today.

>> i'm not going out with you dressed like that.

>> reporter: there are clues to the character. if one follows the trail of england's most famous detective.

>> here we are in this dingy alley way and we still have the old gas lamps .

>> reporter: the landmarks and streets of holmes ' error still exist today. his rooms at 2 1 b baker street offer up clues. he still receives letters here every day. she wants his help. and this is his chair where he would solve complicated crimes, calling especially difficult cases a three-pipe problem. but the mystery here is that sherlock holmes never existed at all. he is a fictional character created by sir sauer -- arthur conan doyle in 1887 . there are thousands of followers keeping track of the adventures of sherlock holmes . a man good with a gun. able to use science to catch criminals.

>> i had a small practice in the country --

>> reporter: and using the power of deduction to solve crimes. but is he sexy?

>> i find intelligence sexy. he's pretty hyper intelligent.

>> reporter: his popularity is phenomenal.

>> french, german.

>> chinese. portuguese.

>> it's all over the world. it's huge.

>> reporter: the english have named pubs after him. there's even a beer called sherlock holmes .

>> to sherlock.

>> reporter: warm beer naturally. roger johnson heads the sherlock holmes journal and says understanding the popularity of the character is as elementary as dr. watson.

>> don't put a puns, watson.

>> puns?

>> i think it's the fact he's not a superman. he has no super powers . he has human powers very highly developed, but you can just about imagine i can do that.

>> reporter: perhaps that explains why so many people have succeeded in portraying holmes , just a guy with a cap who can tolerate warm beer .

>> good morning.

>> reporter: robert downey , jr. was the last big actor to portray sheryl oklock holmes but we can be certain there will be more. as holmes would say, it's rather elementary, my dear matt.