La montaña y el volcan mas alto de Mexico. Mide 5,636 metros (18,490 ft) At 18,490 ft, this is Mexico's highest mountain and volcano. A companion peak lying about six km to the southwest of the Pico de Orizaba is the Sierra Negra, at 4,640 metres (15,223 ft). This subsidiary peak, though far lower than its massive neighbor, is still higher than anything in the 48 contiguous states of the U.S., and on its summit, serviced by the highest road in North America, is one of the world's premier astronomical instruments, the Large Millimeter Telescope.