Pi Symphony: The Ruse Performance Movement I.
Pi Symphony orchestral performance in Ruse, Bulgaria, Nov. 19th, 2010
The melodies and rhythms are based on the numbers of π (3.14159…etc), which describes the ratio of a circle’s circumference to its diameter.
To read more about how this came to be written, see http://www.pisymphony.com/gpage.html
There is also another work based on π called What pi sounds like
Today is pi day, and to celebrate, we bring you a musical representation of π, to 31 decimal places, at 157 beats per minute (which, incidentally, is 314 divided by two).
For more information about this work, please see A musical interpretation of pi
Finally, 18 Wheels on a Big Rig, includes a verse in which they divide the wheels by π.