It's not limited to Nazis. I've taken an interest in preserving CONUS Army Air Defence sites (AKA "Nike Sites"). One of the discouraging aspects of this is how thoroughly sites in liberal jurisdictions have been destroyed, even when there is no need. In most cases the land is repurposed as mere open space or obscure, ill-maintained parks. Sites in conservative areas have fared much better-some even have good restoration potential.
But even on the most devastated sites I've been able to recover the general plan and often operational details and distinctive features (including, on one site in Virginia, three hidden but otherwise pristine missile magazines). I'm leery of publishing my survey data lest I kick off another round of malicious digging and regrading.
History happened. Effacing historical structures because they make us uncomfortable is IMHO akin to burning books
Exactly.
The old Coast Artillery sites are interesting. Many do not realize they even existed.