PHILADELPHIA (CBS) – So why was Philadelphia the place where the Declaration of Independence was written? Why is Philadelphia the Cradle of Liberty?

Steve Frank is a staff historian at the National Constitution Center on Independence Mall. He says it was no mistake that the events of the Revolutionary War were intimately tied to Philadelphia.

“Philadelphia IS where the Declaration of Independence was written. Where the Constitution was written and signed. And the reason for that is that is was the most cosmopolitan city in America at the time. It was the intellectual center and heart of America,” says Frank.

That’s why he says it’s called the Keystone, because it was the corner stone of the new nation.

Frank also says Philadelphia was the most centrally located spot for those colonists traveling from Virginia and Massachusetts. It’s also where the seat of government was located in 1776.

Reported By Kim Glovas, KYW Newsradio