Ive heard about private historic buildings that maintained by a foundation. Why not the Manor House?
Most likely a historic easement was granted to a foundation. This is typically used in Washington DC where the owners are given tax benefits for a façade easement. Since the foundations are 501 c(3) organizations, donations to the foundations are tax deductible. However, the easements are granted for perpetuity; the building must not be demolished and other restrictions apply.
