Depending on how they are configured but I found that one up high where I can put special items, away from unsupervised little fingers.
For the rest, don't put above a bed or above an item of furniture they could use to climb up and potentially hurt themselves.
I used a horizontal shape like this:
So some taller items can also go on the shelves. Keep away from head hitting height but maybe at a level they can use a small step to reach the bottom level.
Now, is there somewhere that meet all those requirements! hahhahahaaaa :)