The world’s largest office building, The Pentagon, is dedicated (Arlington, Virginia)

Signs the military-industrial complex was growing were evident just before America entered WWII, when the sprawling War Department administrative offices spilled out of their headquarters at the National Mall into the surrounding countryside. A new building was desperately needed, and a conference between several officials and the president chose a location in Arlington, Virginia, an intersection of five roads that gave rise to the Pentagon’s pentagon shape. Groundbreaking began almost immediately.

On this day, January 15, in 1943, the Pentagon building was dedicated – at its new spot a mile down the road. President Roosevelt worried its former location would obstruct views of D.C. from Arlington cemetary. The change of scenery did not do much to change the shape of the building, as by then a complete re-design would have added burdensome costs and time.

Ironically, the groundbreaking ceremony for the Pentagon took place on September 11th. The same day 60 years later a terrorist-hijacked plane crashed into the building. Although 125 people inside the Pentagon were killed, the aftermath could have been considerably worse if not for the fortuitous fact that the section hit was reinforced to withstand bomb blasts. The extra strength of the structure and added safety measures no doubt saved lives after the attack.