Visit any well equipped photographic studio and amongst the range of soft boxes available to provide diffused light, you are bound to find a large octagonal “octabox”, “octodome” or similar. I’m not sure what it is about 8 sides that makes it so appealing; I’ve read some opinions that it gives a more natural catchlight in the eyes of your subject. More natural than what? Square and rectangular boxes and reflector panels. The octagon is a shape that is still easy to construct but comes closer to the circular shape of the iris.
Ely Cathedral has a similar story to tell. In February 1322 the monks thought an earthquake had struck, but in reality the central tower of the building had collapsed into the nave of the great church. It’s thought that the construction of the nearby Lady Chapel was the cause. The replacement needed to be more stable and firmer foundations could be found further out suggesting a larger tower. Rather than another square, the opportunity was taken to create an octagon, easier to fit into the existing structure but regardless of the shape it was too large to risk the weight of another stone tower. Timber covered in lead provided the solution as could be seen from the external view I shared a few days ago.
That external view is impressive, but internally it is exquisite.