Simplify the following text for a Grade 10 native English-speaking person.
Original: A manor house or fortified manor house is a country house , which has historically formed the administrative center of a manor ( see Manorialism ) , the lowest unit of territorial organization in the feudal system in Europe .
Simplified: A manor house or fortified manor-house is a country house , which has historically formed the center of a manor ( see Manorialism ) .