Vertical structure, usually solid, that defines and sometimes protects an area
Wall
A wall is a structure and a surface that defines an area; carries a load; provides security, shelter, or soundproofing; or serves a decorative purpose.
There are various types of walls, including border barriers between countries, brick walls, defensive walls in fortifications, and retaining walls that hold back dirt, stone, water, or noise. Walls can also be found in buildings, where they support roofs, floors, and ceilings, enclose spaces, and provide shelter and security.
Text adapted from Wikipedia and Wikivoyage, CC BY-SA 4.0. Photograph: Wikimedia Commons (see Commons), Wikimedia Commons.