The European classics are the cities that were part of the original, early ages when the foundations for today's Europe were laid. Democracy, culture, art, power, languages - the Europe we know today.
When democracy was introduced in Athens in 408BC, European civilization reached a turning point in history. Art reached new levels, with a sophistication and in cases anatomical precision never seen before. Greek art was so accomplished that the Roman Empire tended to copy the Greek styles and methods rather than develop their own.
The Roman Empire was the leading power in Europe between 100BC and 400AD and spread its culture to all the countries and regions it occupied. Rome today is built around the Forum, the birthplace of the Roman Republic with its triumphal arches and temples in impressive shape after centuries of being buried under dirt and mud from the annual floods of the Tiber River.
France really made its mark when Napoleon came to power and began the French expansion through military campaigns and the cultural influence the French presence had on the occupied countries. Paris was designed with wide boulevards for military parades and the wealth brought back is visible in the architecture and grandiose buildings even today.
When the viking age began around 800AD, Danish influence spread rapidly - England, France, Russia, the Ottoman Empire, wherever there was a coast or a river the vikings went. Vikings either raided or settled in Europe, hired to defend their new homes from other vikings. Today you can see viking fortresses, viking ships, viking chieftain burial sites and working viking museums and experience viking life firsthand in Denmark.