A school girl walks past lines of "skulls" on poles in a theatre in Mexico City where artists are assembling an altar for next week's Day of the Dead celebrations October 24, 2007. The altar, known as a "tzompantli", is a wall the Aztecs made of the skulls of humans who had been sacrificed to honor their gods. The giant Day of the Dead altar will be assembled in Mexico City's Zocalo main square next week as part of Day of the Dead celebrations.