The fountain is known also under the name Aquarius. It is made of sandstone and shows the sea god Triton. In 2004 it was completely restored.
Wikipedia (German) http://de.wikipedia.org/wiki/Tritonenbrunnen_%28Aachen%29
Address 69 Kaiser-Friedrich-Allee, Aachen 52074, Germany
Coordinates 50°45'12.985" N 6°4'12.734" E