Where should a mantle be placed?

I'm curious, where exactly should a Mantle be placed in a room? Is there a specific area or wall that it should adorn, or does it depend on the overall design and aesthetic of the space? Is it a matter of personal preference, or are there practical considerations that should be taken into account when deciding on the placement of a mantle? I'm eager to learn more about the art of decorating with mantles and how to incorporate them into my own home decor.