I snapped a picture, then went home to do some research for other circular shelving sources. Sadly, most of the ones that I found were rather expensive. Does anyone have any resources for less expensive circular shelves? Do tell! In the meantime, check out some of the beautiful designs I found.
1. Kansai Bookcase, Anthropologie (University Village, Seattle), $1298
2. Circular Walking Bookshelf, of The Archive Series by architect, David Garcia
3. FlexiTube Shelving, Kisskalt Designs, request a quote at Architonic.
4. Modern Zyk Art Deco Circular Shelves, $6500
Images: 1. Andie Wurster, 2. David Garcia, 3. Kisskalt Designs, 4. Modern Zyk Designs, Austria

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Wow - that first bookshelf set up reminds me so much of Frank Stella!
Could that walking bookshelf be any cooler? I've never seen anything like it!
This may be a little kooky, but as far as mimic-ing the first one goes--I'm seeing two hula hoops (painted a solid color, or maybe not) one mounted to the wall, then normal bracketed shelves mounted over it, with the ends cut to fit inside the circles, then the other hula hoop mounted on the front. It wouldn't be as fabulous as the Anthropologie shelving, but it sure wouldn't be $1300
I feel like I've seen that flexitube shelving as a diy before, but I can't remember what the tubes were. Maybe a canvass of my local hardware store is in order.
Maybe the tubes were Sono-Tubes which are used as forms to pour concrete? They're available as wide as 30" diameter "off the shelf".
Any way to figure out the origins of the throw pillows in this picture?
Ah, never mind - assume from Anthropologie. (Duh.)
Doubter, here. I'd rather have my roundness (and I do love circles) in something more pragmatic than a device intended to hold rectangular objects.
(The walking bookshelf is cool as an art installation, but I can't imagine living with it unless you never read your books -- and live in a huge empty loft.)
Give me a moon gate, or a round window, or circle-motif murals, or an ottoman, or large gorgeous platters, or a star-burst mirror, or any of a number of other circles -- but not shelves.
'Necessity'? I do not think it means what you think it means.