"Why did the renovation take so long?," asks Steven Vogel of The Washington Post.
"The building had to be stripped down to concrete columns and rebuilt from slab to ceiling, yet still operate as the Defense Department headquarters 24 hours a day, 365 days a year. Constructed for an era of manual typewriters, the Pentagon needed to be entirely reconfigured to meet modern communications and technology demands," he writes.
As it turns out, the 9/11 attacks helped expedite the renovation. Vogel explains, "The project was originally scheduled to be completed by 2007, but by 1999, the date had slipped to 2014. After the attack, however, Congress added funding so that the project could be completed by 2011."