This week I’d like you to start a discussion thread that answers the following

“Civilization has thousands of years’ experience with fixed fortifications.  What commonalities have all these “walls” experienced?”

Please – don’t go with just the basics, such as they all failed or fell.  I want you to think and write critically about these significant topics.  Go beyond the basics.  Go past the surface and look for the deeper context behind the commonality so that you can justify your statement?

Response should be 250 words. No need to write it in any format. It is simply a discussion thread.