Thank you for the little tour of the place. I've never been there, but now I can see it'd be a place to visit someday.

having worked with historic properties under various state and federal designations let me comment the there are a number of different designations and all have varying degrees of restrictions from moderate and reasonable for a structure of national significance to the insanely restrictive even for structures of mostly local or regional importance. 
In the most common form (when I was involved c. '80s and '90s), the Federal "Natl. Register of Historic Places", the owner is relatively free to do what he wants (as long as the legal "permitting process" is followed) UNLESS federal $$$ are somehow involved. 
 
However in practical terms for a private owner the "permitting" process can be lengthy and legal costs expensive. Then there can also be multiple overlapping layers of  federal, state, and local historic designations, restrictions, and processes 

Locally the agency I was involved with was able to get a local but nationally significant railroad depot owned by AMTRAK designated as a Ntl Historic Structure (without Amtrak's approval---not sure than can be done now) and AMTRAK prevented from demolishing portions and "modernizing the rest because of their receipt of federal operational funding at the time.
However we also organized a local friends of the depot group that undertook local fund raising for restoration and several local garden clubs that took on the ongoing care of the building and grounds.  Now has a very cooperative and congenial relationship with the AMTRAK organization.      IT CAN be Done

not sure why but the pictures did not show other then a box and a red X on it?