Gothic architecture
Sens Cathedral (begun between 1135 and 1140) was the first Cathedral to be built in the new style (St. Denis was an abbey, not a Cathedral). Other versions of the new style soon appeared in Noyon Cathedral (begun 1150); Laon Cathedral (begun 1165); and the most famous of all, Notre-Dame de Paris, where construction had begun in 1160.
Hexafoil
A key component to Gothic architecture is a strong design principal involving geometry and harmony. The hexafoil design is implemented in various Gothic buildings constructed in the 12th through 16th century. The traditional design is used in cloisters, triforiums and stained glass windows of famous buildings such as Notre-Dame, Salisbury Cathedral, and Regensburg Cathedral. Stone cut-out hexafoils are displayed in a plate tracery style in the Salisbury Cathedral, creating a pattern along the triforium.