A fortified house or fortified mansion, from French maison forte [fr], is a type of building which developed in Europe during the Middle Ages, generally with significant fortifications added. During the earlier Roman period it was common for wealthy landowners to construct unfortified villas on their lands. After the fall of Rome, increased social instability and military conflict necessitated more austere, defensible types of structures. A castle is a type of particularly well-fortified residence. In English-language academic works of castellology, the French term maison-forte is also used, more seldom unhyphenated (maison forte).