What is Ancient House?

Legal Definition
One which has stood long enough to acquire an easement of support against the adjoining land or building. 3 Kent, Comm. 437; 2 Washb. Real Prop. 74, 76. In England this term is applied to houses or buildings erected before the time of legal memory, (Co.oke, Inch Acts. 35, 109.) that is, before the reign of Richard I., although practically any house is an ancient messuage if it was erected before the time of living memory, and its oriein cannot be proved to be modern.
-- Black's Law Dictionary
Legal Definition
One which has by lapse of time acquired an easement of support.
-- Ballentine's Law Dictionary