Cross-window

A cross-window is a window whose lights are defined by a mullion and a transom, forming a cross.

Characteristically the rectangular window is divided into four individual lights by a mullion and transom in the form of a Latin cross.

The window cross was original made of stone ('stone cross-window'); not until the Renaissance and Baroque periods did the timber cross-window emerge (e. g. on the abbey castle of Escorial and on other buildings in the Herrerian style).

Where the transom is in the middle, the window is divided into four lights of equal size.

Later the windows were often divided into six lights, the two upper ones often being joined and forming a type of fanlight.