Outer walls of Caen castle, Normandy, France (about 1050 AD) From Roman castra to medieval castles Rich Romans didn't live in castles. They lived in villas. But Roman soldiers lived in military forts [...]
Carcassonne (1060s to 1240s AD) Where is Carcassonne? Carcassonne, on top of a hill where you can see for miles, has always been important for any army that wanted to [...]
Outer walls of Caen castle, Normandy, France What is Caen castle? This is the castle that William the Conqueror built before he left to conquer England, to defend his own territory in Normandy, [...]
Elevation of Amiens cathedral (begun 1220 AD) Where Chartres cathedral had a full gallery above the side aisles, Amiens has only a thin false gallery like Reims, with windows behind it that let in [...]
Façade of Amiens cathedral in France Why did Amiens build a big cathedral? Amiens is not far from Reims, in northern France, and when the bishop of Reims began building a big new cathedral in [...]
The Romanesque Abbaye aux Hommes, in Caen (about 1050 AD) Vikings settle in Caen Caen is a port town in north-western France, on the Atlantic Ocean. When the Vikings invaded France in the 700s AD, [...]
Caen - Abbaye aux Dames What is the Abbaye aux Dames? Matilda of Flanders ordered her architects to build this Christian church about 1050 AD in her capital at Caen. (Find out why.) The Abbaye [...]
Aachen cathedral (begun 792 AD) One of the first ambitious buildings in Western Europe after the fall of Rome was Charlemagne's chapel at his capital of Aachen (now in northern Germany) about 792 [...]
Tangents: This line is tangent to a circle. What is a tangent? A tangent, like a sine or a cosine, is a mathematical way of thinking about a kind of movement that happens [...]
Sine wave In order to save energy, many, many things in nature move in a kind of repeated pattern we call a sine wave: water waves, sound waves, light waves, [...]
