EXCEPT!!!
If you have a structure (such as a home) on the National Register, you can't alter the outside in any substantial manner, but if it is financed through FHA, or is repossed by HUD, they, if they so judge, can condemn the structure and have it destroyed, National Register or not.
When a couple of National Register Airplane hangars here were demolished for Highway improvements, to fulfill the requirements, they were thoroughly photographed and measured. Then the wrecking balls came in and it was bye-bye B-17 hangars... Hello interchange.
Rick