Pennsylvania's largest city, Philadelphia stands abreast with Boston when it comes to discussing the most historically significant US cities. After all, this is where the "Declaration of Independence" and the Constitution were drafted, revised and signed. Additionally, it was in Philadelphia's Tun Tavern that the very first marines were recruited in 1775, and the city even served a turn as the nation's capital from 1790-1800 while Washington , DC was under construction.

It's safe to say that this has been a place of forward thinking since its founding in 1682. After all, William Penn anticipated the tenants of modern urban planning with his earliest layouts for "The City of Brotherly Love," calling for a rectilinear street grid and five prominent public squares. Obviously, he was onto something, as even with today's heavy automobile traffic, Philly has always been easily navigatable.

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