Garden sheds used to be dank, dusty outbuildings designed solely to store lawn mowers, hoses, tools and pots. No longer. Today's garden shed is still big on storage, but it also has lots of style.

Mark Twain had a garden shed; he called it “the loveliest study you ever saw…octagonal with a peaked roof, each face filled with a spacious window…perched in complete isolation on the top of an ...