Medieval architecture

Religious Architecture

The Latin Cross plan is modeled after the Roman Basilica, it consists of a nave and two sections half its size flanking it, and the altar stands at the far end (the small end of the cross). Also, cathedrals influenced or commissioned by Justinian employed the Byzantine style of domes and a Greek Cross (resembling a plus sign), centering attention on the altar at the center of the church.

Romanesque

Before about the 12th century, cathedral-builders used the Romanesque style. This style put a lot of stress on the walls, forcing them to be very thick and without windows. The time of these churches truly could be called the Dark Ages. The openings were rounded arches, a Roman invention in archicture. Romanesque buildings had very little adornment.

Some Romanesque Cathedrals

St. Marks
Pisa
Santiago de Compostela
St. Etienne
Jumieges

Gothic

In the 12th century, though, Abbot Sugar (shoo-gare) came up with the flying buttress which proved a great innovation in supporting buildings. These beams came out and down from the building, resting much of the weight on the ground outside. The walls could then become thinner and even have windows. The windows installed contained beautiful stained glass, showing stories from the Bible and from lives of saints. Another trademark of the Gothic style is the pointed arch. Such new elements of design allowed cathedrals to go taller than ever, and it became something of a contest to built a church as high as possible.

Some Gothic Cathedrals

St. Denis
Chartres
Notre Dame (actually begun as Romanesque, but completed as Gothic)
Cathedral of Seville

Also built in the Gothic style: Westminster Abbey

Secular Architecture

Medieval secular architecture mainly served for defense. Castles and fortified walls are the most notable non-religious buildings that remain. Windows were made as cross-shaped for more than decorative purposes, they were a perfect fit for a crossbowman to safely shoot at invaders from inside. Crenelated walls (battlements) were employed for archers on the roofs to hide behind when not shooting.