Welcome to the website.
I'd like to refer you to the thread posted by kenny1999 yesterday at 23:44 (problems with "where" and "which').
You can say either this way:
Stratford is the town where Shakespeare was born.
or this way:
Stratford is the town which Shakespeare was born in.
If the relative clause is "which" you need to have a preposition (here, in) in your sentence either at the end of the sentence or right before "which".
Stratford is the town in which Shakespeare was born.
Interested in Language