What architectural features made Reims Cathedral a High Gothic building?

Reims Cathedral is considered a masterpiece of the French High Gothic period due to its sophisticated integration of structural engineering and aesthetic unity. Its status as a High Gothic building is defined by several key architectural features:1

• Advanced Structural Engineering: Reims utilized the core Gothic innovations of ribbed vaults, pointed arches, and flying buttresses. These elements allowed for a soaring verticality and the support of a massive, tall structure while enabling the walls to be opened up for large windows.23
• Bar Tracery: The cathedral is notable for its early and sophisticated use of bar tracery, which allowed for the creation of larger, more complex window designs.14
• Unified Design: The building exhibits a highly unified appearance, emphasized by the use of nearly identical window types in the aisle and clerestory levels, as well as complementary rose windows on the west facade and transepts.1
• Interior Elevation: Following the influence of Chartres Cathedral, Reims abandoned the traditional tribune gallery to maximize the size of the clerestory, allowing for expansive glazing that dominated the interior light.3