The Columbia Encyclopedia, Sixth Edition. 2001-07.
Piedras Negras, ancient city, Guatemala
(py´thräs n´gräs) (KEY) [Span.,=black stones], ruined city of the Classic era of the Maya, NW Petén, Guatemala, in the Usumacinta valley. Reaching a peak of sculptural achievement (according to one dating system, between 731 and 795), Piedras Negras developed some of the finest pre-Columbian stonework.