AthensAthens - One of the most important cities of the ancient world for a multitude of reasons.  Many historians consider it the birthplace of democracy (although this is debatable).  Regardless, its political system allowed thought to flourish in a variety of fields.  Math, science, art, literature and medicine all made tremendous strides in this one city in only a 50-year period in the 5th century B.C..  It is considered the single-most significant center upon which Western culture is based, and its famous Parthenon is probably the most iconic image of  Western Civilization.