Bonampak

The explorer Jacques Soustelle called Bonampak "a pictorial encyclopedia of a Mayan city." Built along the Lacanjá River in the seventh and eighth centuries and eventually abandoned to the jungle, the city remained undiscovered until 1946. Even now it remains more difficult to get to than most other Maya sites (save for Yaxchilán, which still requires a one-hour jungle boat ride to reach). Bonampak means "painted walls" in Maya, and the site is known for just that: beautiful murals depicting the life of the ancient Maya. The three-roomed Templo de las Pinturas has remarkably well-preserved murals still bearing ochre and faience colors.

Source: http://www.pbs.org/wgbh/nova/maya/worl_sans2_01.html