Pictures should hang just above eye level. There is great debate over what "proper eye level" is. Some say "eye level" should be considered as if viewers were standing. Others say "eye level" should be considered as if viewers were seated. Still others say that "eye level" should be determined according to the primary use of the room. (This means, if most of the time people are standing in the space, like a hallway, then "eye level" should be directed at viewers who are standing. In a room where viewers will spend the majority of the time seated, like a living room, 'eye level" would be from a seated position.)
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