A mansion is a large dwelling house. U.S. realtors define a mansion as a dwelling of over . A traditional European mansion was defined as a house which contained a ballroom and tens of bedrooms. Today, however, there is no formal definition beyond being a large and well-appointed house.

The word itself derives (through Old French) from the Latin word mansiō ("act of remaining or staying", a verbal noun from manere "to remain" or "to stay".) In the Roman Empire, a mansio was an official stopping place on a Roman road, or via, where cities sprang up, and where the villas of provincial officials came to be placed. The Scots word "manse" originally defined a property large enough for the Minister of the parish to maintain himself, but a mansion is no longer self-sustaining in this way (compare a Roman or medieval villa). 'Manor' comes from the same root — territorial holdings granted to a lord who would remain there — hence it can be seen how the word 'Mansion' came to have its meaning.

History

The "country house," as it is known in English speaking places, is a distinct species of mansion.

In the past, it was fashionable for the elite society of Europe to pursue the social circuit from country home to country home, with intervals at town homes, so unfortified country houses supplanted castles and the modern mansion began to evolve.

It was in the 16th century that mansions really began to be built in a completely unfortified and gracious styleFact: date=March 2008, with gardens, parks, and drives. This was the era of Renaissance architecture. Hatfield House is a superb example of a house built during the transition period in EnglandFact: date=March 2008. In Italy, classic villas such as Villa Farnese and Villa Giulia were typicalFact: date=March 2008, albeit individually diverse forms, of the new style of mansion.

The uses of these edifices paralleled that of the Roman mansions. It was vital for powerful people and families to keep in social contact with each other as they were the primary moulders of society. The rounds of visits and entertainments were an essential part of the societal process, as painted in the novels of Jane Austen. State business was often discussed and determined in informal settings. Times of revolution reversed this value. During its revolution, France lost a large part of its country homes to incendiary committees, who destroyed the estates as a reaction to/rejection of the ancient régimes.

Until World War II it was not unusual for a moderately sized mansion in England such as Cliveden to have an indoor staff of 20 and an outside staff of the same sizeFact: date=March 2008, and in ducal mansions such as Chatsworth House the numbers could be far higher. In the great houses of Italy, the number of retainers was often even greater than in England; whole families plus extended relations would often inhabit warrens of rooms in basements and attics. It is doubtful that a 19th century Marchesa would even know the exact number of individuals who served her. Most European mansions also were the hub of vast estates. A true estate (the medieval villa, French ville) always contains at least one complete village and its church. Large estates such as that of Woburn Abbey have several villages attached.