Q. What is it supposed to be on the show?

A.  Within the context of the Westworld experience, Sweetwater is the main Old West town, where visitors to Westworld first arrive by train, and become acclimated to the Westworld experience. It is where you'll find the saloon/brothel where Maeve works, and where Dolores meets Teddy as part of their daily loop.

In real-world context, Sweetwater is artificial town populated by robot 'hosts', playing their programmed roles as the citizens of the fictional Sweetwater, and interacting with the theme park visitors.

Q. When do we see it?

A.  In virtually every episode, beginning with Episode One.  If one can say that there is a central location for this wide-ranging series, Sweetwater is it.

[ It should be noted that in Season 2 of Westworld, Episode 6, the Japanese town in "Shogun World" (which mirrors Sweetwater in many respects) was also shot at Melody Ranch, with the sets there modified to resemble an Edo-period town. The Japanese garden, on the other hand, was filmed at a completely different location..].

Q. What is it in real life?

A.  A movie ranch.

Q. Where can I find it in real life?

A. Sweetwater is actually Melody Ranch, which is what is known in Hollywood as a movie ranch.

That's not to say that Melody Ranch is some type of amusement park, it is not.

Don't mistake it for something like Knott's Berry Farm.  Movie ranches are all about business, not play – except that the business, in this case, is movie-making.

Movie ranches are the dependable locations where the studios film when they need to show wide-open rural spaces, especially in Westerns and other films that set are in the past, without the distraction of modern buildings or palm trees popping up in the background to spoil the illusion.

Here is a photo of Melody Ranch from their website:

From the beginning, Westerns were a staple of movie-making, and they later became a staple of early TV.

Westerns required backgrounds that looked like the Old West, not downtown Hollywood.

Because cameras and lighting equipment used to be heavy and difficult to move around, and because virtually everyone involved with the movie-making business lived in Southern California, the studios were understandably reluctant to travel to other states when they needed to shoot scenes of the old West or other rural scenes.

Some of the studios built Western town sets on their back lots, but that didn't work when they needed to show cowboys (or knights in shining armor) riding across a panorama of sweeping plains and rolling hills. They needed "land, lots of land...", open, undeveloped land that could pass for the Old West.

Fortunately, Los Angeles is surrounded by mountains and rolling hills, which were undeveloped and still in their natural state, and that provided perfect locations for filming those kind of rural scenes.  (Along with the perfect weather, that geographical feature was one of the things that drew filmmakers to Southern California in the first place.)

The movie studios quickly bought up huge parcels of open land in those hills, and used them essentially as a convenient extension of their back lot, just a relatively short drive from their actual studios.  Why drive all the way to another state when you can fake it in your own back yard?

Independent movie ranches also popped up to take advantage of the need, with some of them building Old West towns to lure studios to film on their property (at a price, of course).

Melody Ranch was just such an independent movie ranch. It featured an elaborate Western town set, which was used in countless Western movies and TV shows. The Sweetwater scenes on Westworld are filmed on that permanent Western town set. (They even brought in trains during the production, since the ranch does not normally have trains as part of the set.)

For a while, Melody Ranch was owned by singing cowboy/actor Gene Autry, who kept his horses there, broadcasted a radio show from the property, and even titled one of his popular Western movies "Melody Ranch".

Movies and TV shows shot at Melody Ranch include the Western classics "High Noon" and "Stagecoach", as well as countless TV shows such as "The Lone Ranger", "Gunsmoke" and "Wyatt Earp".

More recently, they filmed the series "Deadwood" at Melody Ranch.

You can read more about it's history here.

Melody Ranch is located in the hills east of Santa Clarita, at 24715 Oak Creek Avenue, in Newhall, CA.

That's about 30 miles northwest of downtown Los Angeles.

Although most movie ranches are off-limits to the public, melody ranch does allow for reserved tours, and is usually open once a year for the annual Cowboy Festival.  See their website for more info.

Here is a map link.   And here is an aerial photo of the Western town.

There is no Google StreetView here, so here's a Bing StreetSide view of the entrance.