The fine art term Fresco derives from an Italian word and refers to painting done directly on moist fresh plaster or lime mortar on the wall. The dried pigments are ground into a limewater paste and worked into the wall's surface.
Frescoes were popular during the Renaissance.
In ancient Rome, frescoes were also popular. An article in Ancient History on About.com describes the technique in detail: Fresco Preparing and Painting, The Art of the Fresco Was An Ancient Painting Technique on Fresh Plaster.