How old does something need to be to be heritage-listed?
National Register of Historic Places
In American historic preservation, the fifty-year rule is the generally held belief that a property cannot be listed in the National Register of Historic Places unless it is at least fifty years old. Actually, this rule is not a hard rule at all; it is an exception to the National Register's criteria for evaluation. As stated by John H. Sprinkle, Jr., Deputy Director of the Federal Preservation Institute, "this 'rule' is only an exception to the criteria that shape listings within the National Register of Historic Places. Of the eight 'exceptions' [or criteria considerations], Consideration G, for properties that have achieved significance within the past fifty years, is probably the best-known, yet also misunderstood preservation principle in America."
Grade I listed buildings in Suffolk Coastal
In the United Kingdom, the term listed building refers to a building or other structure officially designated as being of "exceptional architectural or historic special interest"; Grade I structures are those considered to be "buildings of "exceptional interest, sometimes considered to be internationally important. Just 2.5% of listed buildings are Grade I." The total number of listed buildings in England is 372,905. Listing was begun by a provision in the Town and Country Planning Act 1947. Listing a building imposes severe restrictions on what the owner might wish to change or modify in the structure or its fittings. In England, the authority for listing under the Planning (Listed Buildings and Conservation Areas) Act 1990 rests with English Heritage, a non-departmental public body sponsored by the Department for Culture, Media and Sport.