Yo Janina, I have an Idea: We had a series of "Continent Contests", and there was a Classical Antiquity contest, so how about "Historical Periods contest series"? This is how I see it, in brackets there are some topics for pictures:
1. Prehistory (Evolution, Early Hominids, Ice Age, Neolithic Revolution, cave paintings, first cities (Mohendjo Daro, Catal Huyuk))
2. General Antiquity up to Migration Period (not only Greece and Rome, but also Mesopotamia, Egypt, Middle East, etc)
Middle Ages (Rise of Islam, Vikings, Bysantine Empire, Black Plague, Knights, Crusades, Feudalism and Pre-Columbean Americas)
3. Rennaisance and great discoveries (Leonardo da Vinci, Christopher Columbus, Ferdinand Magellan, Michelangelo, Medicis, dawn of firearms, Conquistadors in America)
4. 17th and 18th Centuries: (Pirates, Highwaymen, Wars of the Period, Baroque art, Louis XIV and his court, Philosophers, Age of Illumination, Inventions, French and American Revolutions, Ottoman Turkey, Composers: Bach, Mozart, Haendel, Beethoven, Haydn)
5. Years 1800-1914 (Napoleon Bonaparte, Vienna Congress, 19th century artists, Writers and composers, American Civil War, Wild West, Industrial Revolution, Colonialism, Victorian England, Scientists of the period, inventions (Steam engines, electric Lights, Airplanes, Motor Cars, Photography, first movies), Turn of Centuries, Art Deco, Artistic Boheme, up to World War I)
6. Years 1914-2001 (World War I, "Roaring Twenties", Prohibition and Gangsters in USA, Communistic Revolution in Russia, Adolf Hitler, World War II, Nuclear Energy, fifties, sixties, and seventies in culture, Space Exploration, Cold War, War in Vietnam, Fall of USSR, Computers and Internet, eighties and nineties in culture, basically everything that happenned between WWI and attack on WTC)

Freude, schöner Götterfunken,
Tochter aus Elysium!
Wir betreten feuertrunken,
Himmlische dein Heiligtum!
Deine zauber binden wieder
Was die Mode streng geteilt;
Alle Menschen werden Brüder,
Wo dein saftner Flügel weilt!