Via Spiegel:

They may only be a series and red and brown spots, but they still constitute one of the most important works of art ever made in Central Europe. The spots were discovered on stones in a cave in southern Germany, and are the oldest known signs of painting ever found in the region.

Archeologists discovered the four stones in the Hohle Fels cave near the town of Schelklingen near the southern German city of Ulm. They are around 15,000 years old, according to Tübingen University archeologist Nicholas Conard