Go to Table of Contents of the analysis (which has also a statement on purpose and manner of analysis and a disclaimer as to caveat emptor and my knowing anything authoritatively, which I do not, but I do try to not know earnestly, with some discretion, and considerable thought).

The most important thing which must be kept in mind with Kubrick's films is there is the surface or principle story and then the internal or sub-story. In many of his films, if we're really paying attention, set elements pretty much immediately destroy the surface naturalism. One may not notice this destruction the first, second or third time one watches the film. Through constructive disorientation and disconnectedness, and sleight of hand as to where our eye focuses, Kubrick, the magician, intentionally obfuscates these elements that destroy the overt and naturalistic story line. The surface story lines are the principle ones, and this is maintained and supported by the intentional obfuscation of the deconstructive elements which keep them sub rosa. At the same time, these deconstructive elements are plainly there, alongside his tremendous effort to make things look real and believable, and once we bypass the disorientation and his purposeful refocusing they become a puzzle, annihilating the sense of reality. This destruction of the film's naturalistic story line is difficult enough to conceive of and accept that most people stop at this point and decide these puzzling aspects of Kubrick's films are errors when they are not. They are part of the art of a director cleverly designing the overt story line to be unimpeded by an internal story that tears it apart. Indeed, the sub rosa elements of the internal story may be discreet but they are enough in evidence to complicate the surface story with an aura of attractive, indefinable mystery, which is one of the reasons viewers return to Kubrick again and again. To work with the "reason" and "why of the internal story line is to try to settle into Kubrick's sensibility, examining how these internal stories form a dialogue in his oeuvre with repeating themes and ideas, elaborated upon from film to film. The internal stories haven't a "plot"; they aren't that kind of story. Instead, you have to be willing to deal with comprehending the themes and ideas represented in them as instead ultimately forming a different terrain for the setting of the surface story, guiding and interacting with the overt story and giving it a new form.

Discreet Connections Between the Nathanson Apartment and the Billiard Room Scene (and a Question of Filming Location)

Over and over again I read that the scene of the end pool game with Victor was filmed at the Lanesborough Hotel.

The Royal Suite of the Lanesborough, 1 Lanesborough Place, SW1, was the site of the edge pool-game meeting between Bill and Ziegler.
Source: Movielocations.com

Of at least five London locations, the royal suite at the Lanesborough Hotel at Hyde Park Corner was hired for 10 days in November 1996. Immediately afterwards, the production moved to the Soho drag club, Madame JoJo's.
Source: July 3, 1988 article in the Guardian U.K. "How I tracked down Stanley Kubrick"

The hotel's Royal Suite was used for the fraught over a game of pool meeting between Bill Harford (Tom Cruise) and Victor Ziegler (Sydney Pollack) in Stanley Kubrick's Eyes Wide Shut.
Source: Movielondon.net

Stanley Kubrick's 1999 thriller Eyes Wide Shut used The Lanesborough's most expensive suite, The Royal Suite, as Victor Ziegler's snooker room in the film's pseudo-denouement scene. Bill (Tom Cruise) is summoned by Ziegler (Sydney Pollack) to his home where the two circle his red pool table while the mysterious millionaire gives his explanation of the previous night's events, which included the film's famous masked orgy scenes. The Royal Suite is said to cost up to 8,000 per night, for which you get three bedrooms, a drawing room, study, kitchen, 24-hour butler service, and a chauffeur driven Bentley for the evening.
Source: ehotelier.com

Was the pool room scene, that we see in the film, shot at the Lanesborough? Let's take a look.

Victor's mansion's exterior is the Polish Consulate at East 37th Street and Madison Avenue in New York. The interior hall which leads to the pool room was shot at Luton Hoo Hotel. In shot 499 the butler leads Bill down this hall to the closed door of the pool room.

Eyes Wide Shut - Approaching the pool room

Cut to shot 500 which shows the interior of the pool room and Victor crossing to receive Bill at the door. We have a brief glimpse outside of the hall which is staged to look like that of Luton Hoo but is not.

Eyes Wide Shut - Entering the Pool Room

Eyes Wide Shut - Entering the Pool Room 2

As can be seen in the image below, the woodwork at Victor's is the same as briefly observed at the Nathanson residence when Rosa answers the door for Bill. The room is not the same room and the doors are not the same doors, but the interior woodwork is exactly the same in both the Nathanson apartment and the pool room. Note, too, how the Nathanson residence has in that room a red carpet that anticipates the red felt of the billiard table.

There is not a cut-away shot when the maid exits the room. She exits it directly into the Nathanson entry.

Eyes Wide Shut - Maid enters Nathanson entry

Eyes Wide Shut - Maid in the Nathanson Entry

The Royal Suite of the Lanesborough reputedly has floor to ceiling windows facing Buckingham Gardens. I've seen two photos reputedly of the Lanesborough Royal Suite, one a sitting room and the other a bedroom (I've yet to see anything remotely similar to the pool room in Eyes Wide Shut) and both have floor to ceiling windows, which Victor's pool room does not. The pool room is a corner room with two windows, the one beyond the sofas and the one seen behind a ship model.

Eyes Wide Shut - Window in the Pool Room

If one takes a look at the Lanesborough's surroundings in Googlemaps, there is one but building which could possibly provide a view of a building with close windows. That building is one facing Grosvenor Crescent and Duke of Wellington Place.

Eyes Wide Shut - Next door building

But the style of windows of the above building--one pane of glass--doesn't match any of those viewed out the two windows in the supposed corner room of the supposed Lanesborough Royal Suite room used for a pool room. And, besides, the Lanesborough does not, as far as I can tell, appear to have a corner room that faces out on two close set neighboring buildings from which such windows could be viewed as observed in the shots from the pool room.

As noted above, I've repeatedly read that the billiards scene was filmed in the Royal Suite of the Lanesborough Hotel (once a hospital) in London, the Royal Suite being so exclusive that it's located in a secret location in the hotel that isn't even known but to a few of the hotel's employees.

Until the revealing of Victor's pool room, the Nathanson household had stood out as being curiously unconnected to other locations in the film. I've never seen the location of the Nathanson shoot discussed, and if people have been able to pinpoint the billiard room scene as being the Royal Suite at the Lanesborough, I'm assuming that if the Nathanson shoot was there as well then this would also be known.

IMDB has the lore this pool room scene took three weeks to shoot, but the 1998 Guardian article states that the Royal Suite was booked for 10 days.

To further add to the confusion, Londontown.com gives the Royal Suite's Junior Bedroom as being where Bill and Alice's bedroom was filmed. That assertion is so absurd it hardly merits rebuttal, but here goes. No, no, no, no, no, no, no. This can't be so as the Royal Suite was said to have been booked only 10 days and we have a number of scenes in Alice and Bill's bedroom: the long conversation with Alice and Bill in the bedroom when they're high; the dressing room scenes; the scene after the initial party at Victor's; the long scene when Bill comes home from the "orgy"; the scene when he returns home from this last discussion with Victor. But perhaps this bit of lore exists for a reason as it ties Bill and Alice's bedroom with Victor's home and with the Nathanson home. And, as we shall shortly see, Bill and Alice's bedroom does not map into their apartment. It is one of those Kubrick rooms that is impossible, and Kubrick even presents the impossible room as being in two different locations in the apartment.

In fact, I'm not at all confident that the pool room scene was ultimately filmed at the Lanesborough.

I find in an interview that Jan Harlan states, "Stanley Kubrick changed his mind on the two sets that involved the character of Ziegler. Originally he had selected two locations for the bathroom scene and the scene around the pool table with Tom Cruise. But he changed his mind as he didn't like what he had chosen and this was his prerogative. We had to build sets which took several weeks to finish and I couldn't make a deal with Harvey Keitel's agent that we could live with. End of story. Stanley was delighted to get Sydney Pollack at a later date when the sets were built. There was just one scene we had to re-shoot: the reception at the Ziegler's Christmas party."

This leads me to think that Kubrick didn't like what was shot during those 10 days at the Royal Suite, that a set was built for the billiards room, and that woodwork from that set was also used for the Nathanson apartment.

Even though it seems the billiard room scene was not ultimately shot at the Lanesborough, the film itself even seems to present a connection between not only the Nathanson apartment and the billiard room, but the Lanesborough. When Bill is on his way to the Nathanson's in the cab we see FIRE LANE on the street in such a way that LANE is the word that makes a most lasting impression in the shot.

The view we have of the Nathanson room with the pool room woodwork is so swift and abbreviated that it seems Kubrick intends no conscious notice that it shares that same woodwork, but it does, and thus Kubrick creates a connection between the two households, that connection also remarked upon with the red carpet that anticipates the pool table's bright red felt.

See my full analysis of Eyes Wide Shut at this link
Link to the main Kubrick page for all the analyses.