Reuters:

But what was most striking to those who worked on the project was Apple managers’ insistence on treating the construction of the vast complex the same way they approach the design of pocket-sized electronics.

Apple’s in-house construction team enforced many rules: No vents or pipes could be reflected in the glass. Guidelines for the special wood used frequently throughout the building ran to some 30 pages.

Tolerances, the distance materials may deviate from desired measurements, were a particular focus. On many projects, the standard is 1/8 of an inch at best; Apple often demanded far less, even for hidden surfaces.

And:

Apple’s novel approach to the building took many forms. Architect German de la Torre, who worked on the project, found many of the proportions – such as the curve of a rounded corner – came from Apple’s products. The elevator buttons struck some workers as resembling the iPhone’s home button; one former manager even likened the toilet’s sleek design to the device.

But de la Torre ultimately saw that Apple executives were not trying to evoke the iPhone per se, but rather following something akin to the Platonic ideal of form and dimension.

Fascinating read. Skip the video.