from the World Trade Center that were recovered from Ground Zero, oriented to represent the elevator cores in the two buildings. The steel beams are about and weigh about ; the studs in the steel are in diameter and long with heads that are in diameter. The circular base has a radius of and a circumference of . The length of the circumference of the circle symbolizes the 1 square acre footprint of each tower of the World Trade Center, with a square acre being on each side. The circular base has an area of , which dedicates for each of the 343 firefighters killed in the World Trade Center attack. The tops of the World Trade Center towers have 40 lights that represents the passengers and crew killed in the crash of United Airlines Flight 93, with 20 lights in each tower oriented in a circle. If one stands at the center of the World Trade Center Patio and looks directly at the center of the 9/11 Monument, the line of sight will show where American Airlines Flight 11 crashed into the far side of the North Tower of the World Trade Center and where United Airlines Flight 175 crashed into the near side of the South Tower of the World Trade Center. If one stands at the center of the William C. Daywalt Sr. Memorial Gazebo and looks directly at the center of the 9/11 Monument, the line of sight will show where American Airlines Flight 77 crashed into the far side of The Pentagon and also traces the flight bearing of United Airlines Flight 93 before it crashed in Shanksville, Pennsylvania. History In April 2011, the King of Prussia Volunteer Fire Company received two pieces of steel from the World Trade Center to incorporate into the memorial. Construction of the 9/11 Memorial was originally planned to begin in July 2011, but was moved up a month after the death of Osama bin Laden on May 2, 2011. The memorial was designed by Charles Edwin McDonald Jr. and was constructed by Joseph J. White Jr. The 9/11 Memorial was dedicated by the King of Prussia Volunteer Fire Company on September 11, 2011, which marked the tenth anniversary of the attacks. The dedication ceremony was attended by the general public along with various local, state, and federal officials. The ceremony featured the unveiling of a custom-made motorcycle from Orange