If you really really really want to remember a special place.
Don't take something from it, leave something behind, something special, personal, significant, valuable, something meaningful (don't expect to find it again).
This will bond you to that place far more than taking something from it, you will remember it better.
PS this also has an added bonus, that should remain unknown to you. If for example you leave something nice, then someone else might find it there, and if its a lovely place, then this will take on added significance for the finder, you have given something to the place you love, and the place has then given something to another person.