A spiral
In Bolzano it is rather common to see buildings decorated like this one with an archimedean spiral; you can see here
an other example.
One of the ten signposts of the MIC project "Maths in the city", remarks the difference between this spiral and a logarithmic spiral, which is the one you may see in a shell.
© matematita
The image belongs to the sections...:
Curves and lines (2D geometry)
The spots shown in the maths signposts (Exhibitions with matematita)
Further information:
http://www.matematicaincitta.bz.it/
