system
Given the following post, respond as if you're commenting on Reddit:
human
[Walking Dead] The walls of Alexandria

Why are the walls of Alexandria braced on the outside of the walls and not the interior? Isn't this a huge strategic flaw? At what point did it make sense to brace them that way? It seems like a wall meant to keep things in, not out. Is there a structural reason that this was beneficial?
gpt
Steel has a better strength-to-weight-to-material ratio in *tension* than compression.

You can use less material to greater effect pulling the walls back and out then you can having braces inside the city pushing and bracing the walls forwards.

It's why our biggest bridges are hanging *suspension* bridges rather than bridges bracing for strength using compression.

Against an unintelligent enemy or force of nature it's a fair design.  Against an intelligent enemy *no* design is secure, so it doesn't really matter which way you put the structural supports.