Final answer:
The term 'grille' best describes a structure of crossed strips arranged to form a regular pattern of open spaces, commonly used in architecture for decorative purposes while allowing light and air to pass through.
Step-by-step explanation:
The structure of crossed strips arranged to form a regular pattern of open spaces can be best described using the term grille. This term refers to an architectural element that consists of a grid or series of bars that are either fixed or removable. The purpose of a grille is often decorative while allowing air and light to pass through, as well as providing a barrier. The other options provided, such as treillage which refers to a lattice or framework for supporting climbing plants, mansard which is a type of roof, and piazza which is an open public square, do not accurately describe a structure solely made of crossed strips forming regular open spaces.
An example of grille work can be observed in architectural elements where bricks are laid in specific patterns to create decorative effects. For instance, brick units laid in an angle to create a sawtooth-pattern frame that inscribes a diamond-like perforated brick net can be considered a type of grille. Additionally, elements like horseshoe arches and trilobed arches framing windows, which exhibit delicate interplay between open and built spaces, align with the concept of a grille. The term also finds relevance in examples where recurring arches and openings are characterized by their systematic and geometrically logical arrangement that allows the passage of light and air, contributing both to the functionality and aesthetics of the space.