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

A.  Sub-level 84, otherwise known as "Cold Storage" - the lowest region of the huge Delos corporate headquarters at Westworld (built into a towering mesa). where the company stores defective robot hosts.  It has fallen into disuse and disrepair, and water is gushing from the broken cooling system.

Q. When do we see it?

A.  In Episode 1, when the armed staff ventures down into Sub-level 83 to check on reports of unusual activity.  Walking through the creepy setting, they come to dozens of naked, decommissioned 'hosts', standing at attention, looking far too much like some nightmare scene from Auschwitz.

It shows up again in Season 2, Episode 8, when the Ghost Nation warrior Akecheta finds his way into Delos's subbasement, searching for his dead lover, like some Native American version of Orpheus descending into Hades.

Q. What is it in real life?

A.  An old enclosed shopping mall.

Q. Where can I find it in real life?

A.  This is the former Hawthorne Plaza Mall, at 12000 Hawthorne Boulevard, in Hawthorne, California.

That's just southwest of Los Angeles International Airport (LAX), a few blocks south of the Century (105) Freeway.

The mall opened in 1977, and quickly became the main shopping center for the city of Hawthorne.

It was a large, fortress-like enclosed mall, blocks long, with major department store anchors.  I went there a number of times when it was still a thriving, middle-class mall, little suspecting what the future held in store for the mall.

But by the 1990's it began to fail, a victim of both the low incomes of the surrounding area, and the messy, lengthy construction process of the new Century Freeway, which tore up huge swaths of homes in its path.

(They even demolished the Beach Boys' family home in Hawthorne, to make way for the new freeway.  All that stands there now is a monument to the group, marking the spot.)

The mall slowly lost customers to the other nearby malls (the South Bay Galleria, Del Amo, and Fox Hills), until  the Hawthorne mall finally closed for good in 1999, and now sits as an empty shell of its former self.

But leave it to Hollywood scouts to recognize a potential filming location when they see one.

The empty Hawthorne Mall has appeared in a number of Hollywood productions. 

It's first appearance (that I know of) was in the 2002 Tom Cruise sci-fi epic, "Minority Report", back when the mall was still in good enough shape to play a normal mall (called "Mall City") in the movie.

Later, the mall's exterior parking areas showed up in the 2011 movie version of "The Green Hornet". 

By 2013, it had fallen into such disrepair that the TV series "Teen Wolf" shot a major supernatural battle scene there, no doubt attracted by its now-spooky ambiance - and the mall looked just as decrepit as it does in Westworld.

Here's a screenshot from that Teen Wolf episode:

Look familiar?

Don't bother trying to go there.  It's all boarded up and off-limits.  (And I suspect that if you could sneak inside, you'd probably regret it.)

Here is a map link to the mall.

Here is a Google StreetView panorama of the exterior of the Hawthorne Mall:

And here is an aerial photo from Google Earth.