The will should be kept in a secure place such as safe deposit box or fire proof strong box. But more importantly, your executor should know where it can be found. It is a good idea to give a copy of the will to your executor with a notation where the original will can be located.
If it is kept in a safe deposit box it can be removed by the executor immediately following your death in the presence of an employee of the bank upon proof that you are the proposed executor named in the will.