Which term describes a decorative element typically found on castle walls?

Crenellation refers to a specific architectural feature commonly seen on castle walls. It involves a series of alternating high and low sections, often resembling a tooth-like pattern. This design was not only aesthetic but also functional, as it provided a strategic advantage for defense. The raised sections, also known as merlons, offered protection to those defending the castle, while the lower sections, or embrasures, allowed for arrow or projectile firing. This characteristic is a defining element of medieval fortress architecture, making it particularly significant in discussions about historical structures.

Baluster, on the other hand, typically refers to a small post or pillar that supports a railing, often found in staircases or balconies, rather than in fortification designs. Amphora is a type of ancient vessel used for storing liquids or grains, primarily in Greek and Roman cultures, and has no relation to architectural elements of castles. Camera obscura is an optical device used in the study of light and vision, not a decorative architectural feature. Thus, crenellation stands out as the only term directly linked to the architectural features of castle walls.