Wall

Cobblestone wall is a block designed for decorative purposes such as gardens and are an alternative to fences. There are 2 types: cobblestone walls and mossy cobblestone walls. They work very similarly to fences, as they are 1.5 blocks tall to mobs. Cobblestone walls are more efficient at fencing off mobs than a two-block high cobblestone wall, costing only half as many blocks, and being more space-efficient as well. The drawback, however; is that a skeleton might shoot over the wall, a creeper could explode if a player is standing near the wall or a spider may climb over the wall.

Trivia

 * Interestingly, mossy cobblestone wall's name is based on the old name for moss stone and not the new one.
 * When a fence gate is placed between 2 cobblestone walls (of either type) it will stoop down slightly to match the height of the cobblestone wall.
 * If the fence gate is only placed next to only 1 (mossy) cobblestone wall, or vice versa, it will not lower.
 * Although the cobblestone wall only raises at corners and ends, it will raise to support a solid or non-solid block placed above it.
 * Cobblestone walls function the same way as fences, yet are placed in the building blocks tab of the Creative inventory instead of the decoration tab.
 * Mob heads are the same size in width as the posts on a cobblestone wall.
 * As of 1.4.4 you can no longer walk between 2 cobblestone walls placed parallel from each other with a less-than-one-block-thick space in the middle.
 * You can connect both types of cobblestone walls together but not both types of fences.
 * Unlike fences, if two cobblestone walls are placed one block apart diagonally, you cannot walk between them.

Gallery
Pflastersteinmauer Muret Murek z bruku Булыжниковая стена 圆石墙