'I forgot to mention,' [said Gandalf] 'that with the map went a key, a small and curious key. Here it is! ... Keep it safe!'
And where could be safer than on a Gandalf key-ring...?
Just be sure not to lego of your wizard!
And the website The Tolkienist has launched a series of 75 (the current age of The Hobbit) reasons why you should read The Hobbit before watching the films; my contribution is, as you will see, somewhat joky, but there are 75 reasons – count 'em and see for yourself!