DESIGN IN MATHEMATICS IN DESIGN!!
In one of my architecture classes we studied a building in rome which I believe uses mathematics in its design better than many other things. This building is the Pantheon.
As you can see from the bottom two images, the pantheon's rotunda is a perfect circle, but not only that, its height is the same as its width. The roof is the shape of a perfect sphere. At the top, its height is the exact dimension of the diameter of the sphere that can fit inside the structure.
Beyond the impressiveness of its dimension is the time it was built. It's large dome was unable to be matched until 1700 years later with the use of iron and steel.
The mathematics surrounding the design of the pantheon definitely excedes the math in the physical appearance of any other structure.