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

A.  A campground for Confederados soldiers, and the scene of a bloody massacre.

Q. When do we see it?

A.  In Episode 9, where Logan (who has made himself a general in "the Army of New Virginia") has taken William and Dolores captive.

Angered by William's belief that Dolores is special, Logan decides to teach William a shocking lesson.  He takes a large knife and plunges it into Dolores's stomach, tearing her open and exposing the mechanical mechanisms deep inside the Westworld host.

Only Dolores is special, so her reaction is to grab the knife and slice Logan across the face (demonstrating she isn't limited by Westworld's normal rules), then she grabs a gun and shoots several of the (host) soldiers, before taking William's advice to flee.

After Dolores is gone, Logan and William appear to reconcile, and Logan is sure that he has finally convinced William that the hosts, including Dolores, are just dumb machines. They embrace and appear to reconcile.

But in the morning, a hungover Logan awakens to an equally shocking lesson: overnight, it seems that William has killed every single soldier (host) in the camp, leaving their bloody, dismembered bodies strewn across the landscape.

Logan reaches for a weapon, but William has taken it.  A newly savage and determined William tells Logan he has learned how to play the game, and then he attacks Logan, pinning him to the ground with the knife at his throat, and William makes it clear that he is now in control, telling Logan that he is going to find Dolores, and that Logan is going to help him,

Q. What is it in real life?

A.  A movie ranch.

Q. Where can I find it in real life?

A.  By now, you may have thought Westworld had already used every movie ranch in town.  But you'd be wrong.

They found another one for this camp massacre scene.

Pay attention to the crumbling ruins in the background of this camp scene.  That's the key.

This is one of the outdoor sets at Blue Cloud movie ranch (not to be confused with Big Sky movie ranch, where they filmed the Abernathy ranch scenes), at 20019 Blue Cloud Road, in Santa Clarita / Saugus, CA.

We tend to think of movie ranches as places designed to film Westerns, and most of them are – that is why the term "ranch" started for these filming properties. But there are also smaller, more specialized "ranches" which offer different settings, such as Club Ed (which offers a '50s desert setting), Warner Ranch (which offers a residential setting), and this one, Blue Cloud, which offers a Third World ambience.

Although set in the background of this scene may look like the ruins of an old Mexican village (which fits in well with the geography of this show), this is actually a general set that (with a little set decoration) can be used  as various different locations, including war-damaged buildings in the Middle East

This isn't the only set at Blue Cloud Ranch. In fact, most of the scenes I've seen shot at this ranch location were shot on their generic "Third World Town" street (right next to this ruins area), where most of the buildings are intact, and which can easily be made to look like some distant spot in the Middle East or Africa.  If you see someone on TV venturing into a terrorist lair in Afghanistan, there's a good chance it was shot here.

They filmed the 2012 hit movie “Zero Dark Thirty” here, as well as scenes from “Iron Man”, "Agents of S.H.I.E.L.D." and “True Blood.”

Blue Cloud Ranch is located about seven miles northeast of Six Flags Magic Mountain, in the hills above Santa Clarita, about 12 miles north of Melody Ranch (where they filed the Sweetwater scenes), and about 40 miles northwest of Big Sky ranch.

    Here's a map link.

    And here is a Google Earth aerial view of the sets.