Merlons are the solid, upright sections of a battlement, which is a defensive architectural feature commonly found on castles and fortifications. They alternate with the openings called crenels, allowing defenders to shield themselves while providing a vantage point to observe and attack enemies. Merlons are typically made of stone or brick and can vary in height and design, depending on the style of the fortification. Historically, merlons were crucial for the protection of soldiers during sieges. They were often designed to be thick and tall, providing a barrier against arrows and projectiles. The presence of merlons is a defining characteristic of medieval architecture, particularly in structures associated with European castles and fortified cities.