Never-ending hallway

The never-ending hallway is the main location in P.T.. Its precise location remains unknown, though it is likely connected to the town of Silent Hill in some way or another.

P.T.
The hallway seems to be situated inside a house. In the hallway the player finds four doors: two of them are respectively the hallway's entrance and exit, another one is the bathroom's and the last one seems to lead outside, though it remains closed at all times.

Apart from being quite messy, the place does not seem too odd at first sight. There is a digital clock in a niche which reads 23:59, one minute before midnight, however waiting for a minute does not seem to affect the clock; it does, however, change as progress is made. The hall's bizarre nature is revealed when the player opens the exit door, leading immediately to the entrance of the exact same hallway, albeit with some changes; the first one being that the radio is turned off. The never-ending hallway is indeed a series of "loops" that prevent the protagonist from escaping as the exit door will systematically bring him back inside the same hallway, and remain impossible to open, for as long as a riddle remains unsolved. It is unknown whether each "loop" corresponds to a new hallway or if it is the same one every single time.

Lisa's ghost haunts the hallway. She was presumably living inside the house before she died, and confronts the player several times during his visit of the hallway. Her presence seems to grow stronger as the player progresses through the various loops.

After a certain amount of loops, the hallway gets even more twisted with red tinted lights and paintings of rotating eyes. The layout of the room is slightly different, in an almost maze-like fashion. This may be the equivalent of Otherworld where the previous hallway was in the Fog World, or it may simply be the house next door - possibly in which the second murder took place. The baby in the sink also talks with the voice of the man on the radio, whenever the bathroom is viewed by a newly uncovered peephole. After he stops talking, a message appears above the hole which reads "No turning back now". More frightening messages appear, such as one near the "exit" door mentioning "I can hear them calling to me from hell". After escaping this hellish version, the clock now reads 0:00, implying the real nightmare has begun. After a longer period of time, the game will glitch out and an error message page will be displayed. The player then restarts again in order to solve the final puzzle.

One of the puzzle solution involves the player finding 6 pieces of a torn off picture. After the pieces have been found, there will be a message on the picture "My voice, can you hear it? This sign, can you read it? I'll wait forever if you'll just come to me". The puzzle is optional and can be solved either on early stages of the game or during the final loop.

Trivia

 * There are images of owls on some wine bottles. Images of owls also appeared on rifle ammo boxes, and there were also Woodpecker alcohol bottles in Silent Hill 2.
 * The fact that every new "loop" seems to feature an even more twisted version of the hallway as well as the maze-like construction of the place and the occurrence of disturbing events may mean that the never-ending hallway is invaded by the effects of the Otherworld. It could also be a sort of Nowhere-like area, an area created by the Otherworld itself, from which it is impossible to escape, which would explain the "loop" effect. Each loop may correspond to each parallel universe - (almost) Real World, Fog World, Otherworld, Nowhere, and some slow transition universes inbetween.
 * The hallway shares many characteristics with Silent Hill 4's Room 302, as both are homes that seem perfectly normal at first sight, but that are progressively getting haunted. Many events occurring in P.T. actually recall the hauntings of the room in Silent Hill 4. The presence of a permanent radio as well as a phone, both broadcasting disturbing messages, is also reminiscent of Room 302. Finally, it is impossible for the protagonist to escape from both places, with the main door remaining locked and the only exit leading to alternate realities.
 * It can be speculated that the hallway consists of various Otherworlds, each loop corresponding to a new Otherworld, similarly to Walter's Otherworlds. This could actually be an explanation to the title Silent Hills, plural, as there would be more realities, or possibly even worlds, to explore than in former games of the franchise.
 * At one point during gameplay, the radio mentions a father hanging himself with a garden hose after killing his family. A muffled voice says "umbilical cord" instead of the aforementioned hose.  Umbilical cords are also a notable theme in Silent Hill 4: The Room.
 * The Neverending Hallway shares thematic elements with Junji Ito's short story The Town Without Streets. In each story there's a malevolent force that twists the laws of reality, creating an endless loop.  The difference is that Ito's story takes place in an entire town while P.T. takes place in a single hallway.