1. Your own personal fireproof home safe- Your executor will need ready access to the safe, by combination or key, or both.
Safe Deposit Box
2. Safe deposit box- Make sure your state law does not require banks to seal the box upon death, and consider who else has access to that box. Be certain your survivors know of this location.
3. Leave it with your lawyer- Some law firms have vaults for such storage of wills and trusts, but some attorneys will not store your will, as they may have concerns about the propriety of this practice; specifically, the concern that a deceased client's family may feel pressured to use that firm's services in order to probate the will.
Probate Court Safekeeping
4. The probate court- For a nominal fee, your local probate court may file your will for safekeeping, and produce it only for your named executor, with proof of your death. Consider that this might not be optimal if you happen to move away and perhaps end up retiring in another state.
5. A trust company- If you name a trust company as your estate representative then that company will often hold your will for safekeeping.