Apple has been granted a patent for the cylindrical entryway into its flagship retail store in the Lujiazui district of Shanghai's Pudong sector.

Shanghai's cylindrical variant of New York City's Apple store glass entrance cube

The US Patent and Trademark Office granted patent number 8,544,217, rather aptly named "Glass building panel and building made therefrom," to Apple on Tuesday.

"Glass structures have been around for some time," Apple admits in the patent's Background of the Invention section, but the Shanghai entryway is not subject to claims of prior art, apparently, since the USPTO feels that Apple is entitled to a patent on the techniques used to fabricate it.

The patent describes a structure composed of a series of curved glass panels forming a cylinder, separated and supported by vertical rectangular beams, and topped by a glass roof supported by horizontal glass panels and a horizontal smaller cylinder:

Laminated glass is discussed in three of the patent's 25 claims, and the explanatory text of the patent goes on to describe the advantages of laminates in adding strength to large glass panels and beams. The patent's illustrations, as seen above, clearly relate to the design used for the Shanghai store, but it is not mentioned anywhere in the 22-page document.

The inventors – or, more likely, their lawyers – however, don't want to tie themselves down too tightly to just the Shanghai design, and have peppered the patent text with a healthy dose of qualifiers (our emphasis):

The invention relates ... to a building made using building panels where the building panels may be glass, may include a plurality of glass layers, and may be curved. The building may include glass fins and glass beams for support, and a glass roof. The glass building panels, glass fins, glass beams, and glass roof may be connected together by a plurality of fittings.

So if you're thinking of building a glass structure, take care how you construct it or Apple's crack legal team may come a-knockin' at your front door – especially, it appears, if that door happens to be made of glass. ®