There are no rules as to where to hang a longbell door chime, just a few best practices.
It's a good idea to mount a long bell doorbell where it will be heard in the rooms where you spend most of the hours when you might expect visitors. A location near your front door is desirable as this allows your callers to hear the door chime as they push the doorbell button. This provides feedback that you have indeed been summoned. Ideally, your chosen location treats your guests to the sight and sound of your still resonating long bell doorbell as they enter your home.
In general, a spot between 72 and 78 inches above the bottom of the finished floor to the top of the case is about right if your ceiling height is eight feet. You may choose to mount your chime at higher or lower to suit your taste.
If you are lucky enough to have a door chime niche, The location for your door chime was made for you by a thoughtful designer.
At left a vintage, never used, Kensington by Rittenhouse Long Bell door chime has a commanding presence in a Chicago area home. Meanwhile, an ElectraChime Empire tubular doorbell graces a niche in Minnesota.