Within an ancient Roman city, aristocratic or just wealthy dwellings might be very extensive, and luxurious. Such mansions on one hill in Rome became so extensive that the term palatial was actually derived from the name Palatine hill and is the etymological origin of "palace". Mansions of considerable size and state significance are called palaces.
Following the fall of Rome the practice of building unfortified villas ceased. Today, the oldest inhabited mansions around the world usually began their existence as fortified castles in the Middle Ages. As social conditions slowly changed and stabilised fortifications were able to be reduced, and over the centuries gave way to comfort. It became fashionable and possible for homes to be beautiful rather than grim and forbidding allowing for the development of the modern mansion.
In British English a mansion block refers to a block of flats or apartments designed for the appearance of grandeur. In many parts of Asia, including Hong Kong and Japan, the word mansion also refers to a block of apartments. In modern Japan, a "manshon" (マンション), stemming from the English word "mansion", is used to refer to a multi-unit apartment complex or condominium.
In Europe, from the 15th century onwards, a combination of politics and advancements in modern weaponry negated the need for the aristocracy to live in fortified castles. As a result, many were transformed into mansions without defences or demolished and rebuilt in a more modern, undefended style. Due to intermarriage and primogeniture inheritance amongst the aristocracy, it became common for one noble to often own several country houses. These would be visited rotationally throughout the year as their owner pursued the social and sporting circuit from country home to country home. Many owners of a country house would also own a town mansion in their country's capital city. These town mansions were referred to as 'houses' in London, hotels in Paris and palaces in most European cities elsewhere. It might be noted that sometimes the house of a clergyman was called a "mansion house" (e.g., by the Revd James Blair, Commissary in Virginia for the Bishop of London, 1689–1745, a term related to the word "manse" commonly used in the Church of Scotland and in Non-Conformist churches. H.G. Herklots, The Church of England and the American Episcopal Church).
As the 16th century progressed, and Renaissance styles of architecture slowly spread across Europe, the last vestiges of castle architecture and life changed; the central points of these great house, great halls, became redundant as owners wished to live separately from their servants, and no longer ate with them in a Great Hall. All evidence and odours of cooking and staff were banished from the principal parts of the house into distant wings, while the owners began to live in airy rooms, above the ground floor, with privacy from their servants, who were now confined, unless required, to their specifically delegated areas—often the ground and uppermost attic floors. This was a period of great social change, as the educated prided themselves on enlightenment.