period accuracy

The history of modern swimming pools really dates back just a hundred years or so.  Yes, there are examples of pools, baths and other watershapes from the distant past, but the swimming pool as we know it is something that truly emerged during the 20th Century, mostly after World War II.  Before then, there were probably no more than 50,000 pools built in all of the United States - and most of those were seen as something quite special for their time.   Nowadays, we're far enough into the development of "modern" swimming pools and other watershapes that a small number of "antique" pools have been declared historical landmarks, with those at Hearst Castle being