This is a video I found on the website of italian newspaper La Repubblica, it shows Europe (as continent not as EU) has changed over the past 1000 years: how wars, invasions and political deals have changed borders. Some readers have pointed out imprecisions in this video, however I find this timelapse very interesting has it shows how much the continent has changed, how often borders are established for political reasons with disregards of the populations and the communities that live along them.
similarly the BBC published these maps in which it traces the shifts in beorders within Europe. The artcle refers mainly to the EU, whilst the maps refer also to Europe as continent. http://news.bbc.co.uk/1/shared/spl/hi/europe/02/euro_borders/html/