der Wall (die Wälle in plural) and the wall have similar ideas, but they’re still different enough to be false friends.
Because the German Wall is actually a rampart and its main purpose is protection. It can be an actual (thick) wall, but it can also be just piled up soil or rocks.
And that’s actually also the original meaning of the English wall, but it eventually shifted to be the general word for … well… the walls of a building.
What’s that in German?
Well, there’s two words. Of course.
The main one is die Wand (die Wände), which is the word used for the walls our buildings. And the other one is die Mauer (die Mauern), which is used for outside facing or free standing walls like the wall of a castle or the Berlin wall.
And while a Wand can be made from various materials, a Mauer is always stone.
These two words are fairly useful, but I don’t think der Wall itself is something I’ll need so I’ll put it on the passive vocabulary pile.