A 1,410-ft-tall signal tower in Liberia, formerly used by the U.S. Coast Guard for ship navigation and the tallest structure in Africa, was imploded on May 10. Mark Loizeaux, president of Controlled Demolition Inc., the project's Phoenix, Md.-based subcontractor, says it is the world's tallest man-made structure to be felled by explosives. The tower weighed 520 tons. The government of Liberia approached the Coast Guard for help felling the tower, which was decommissioned in 1997 says Lt. Col. Clement Ketchum, a U.S Army official in Monrovia. The Liberian government evacuated illegal squatters who had built buildings under the tower, but contractors had no reports of damage to those structures at ENR press time.