traceries

Traceries are ornamental openwork patterns, typically in stone or wood, used to fill the upper parts of windows and other openings in architecture. They create a delicate network of slender bars—mullions and transoms—that divide light into geometric or curved shapes while contributing a distinct texture to the façade. Tracery patterns are a defining feature of Gothic architecture and are found in churches and cathedrals across Europe, where they shape both light and visual rhythm.

There are two principal forms: plate tracery, in which the pattern is cut from a continuous stone plate to form the window opening; and bar tracery, where separate stone mullions and bars outline the pattern. Bar tracery allows more intricate shapes and larger openings and became dominant in late medieval architecture. Within bar tracery, regional styles emerged, including the geometric tracery of early English Gothic, the curvilinear or flamboyant tracery of the 14th and 15th centuries, and the strong vertical patterns of the later Perpendicular style.

In construction, tracery patterns are designed to harmonize with the window frame and arch. The effect is primarily decorative, shaping the way light enters the space, though the overall stability of the window is provided by the surrounding mullions and structural elements. Tracery patterns were revived in later periods for interiors and decorative arts, and remain an enduring symbol of medieval architectural technique.