<P> Mansions built during the 20th and 21st centuries usually have specially designed rooms meant to accommodate leisure activities of a particular kind . Many will have a conservatory or greenhouse, while others will have an infinity pool or a home theater . Some have all of these features . The relative importance of these specially designed rooms changes with the times . At the beginning of the 20th century, no true mansion would have been built without a room to house a private library or study, while at the beginning of the 21st century the presence of a room designed for a home theater or cinema is normal . Most recently, mansions have been built with integrated home automation . Some other technology - inclined mansions may even have a bowling alley or a server room . </P> <P> A modern mansion today may not necessarily be limited to a single house standing alone, but like Roman Emperor Nero's Domus Aurea, mansions may be compounds or a grouping of larger houses . The Kennedy Compound is an example of one family building surrounded by large houses on a single plot . In general, whether a house can be called a mansion is contextual--in Manhattan or many cities a 5,000 - square - foot (460 m) house would certainly be described as such, but a similar sized house in the Atlanta suburbs probably would not be . Calling something a mansion indicates a level of grandeur / consumption considerably greater than the norm in that location, with the additional connotation of quality and correlates highly with the housing patterns of the upper class . </P>

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