The Big Bang Theory Wiki

Aerial shot of the building.

The Los Robles Apartment Building, or simply The Building, refers to the apartment building located at 2311 North Los Robles Avenue, Pasadena, California that serves as the residence of Leonard Hofstadter and Sheldon Cooper. When viewed from the satellite photographs (The Countdown Reflection), it appears to be in reality located at 215 South Madison Avenue. Leonard, Sheldon, and Penny occupy apartments on the fourth floor. Adjacent to a lamp store, it is located about a block from Pasadena City Hall, which is visible through Sheldon and Leonard's window. The building is also located near a Chevron Station on Colorado Boulevard, because Leonard makes the excuse that he uses its bathroom when he and Penny began seeing each other for the second time in Season 5.

The apartment building has at least five floors and sixteen apartments (based on the number of mailboxes) which suggests there are two more unseen apartments per floor or the structure is connected to an adjacent building. The Elevator had been broken for several years (predating Penny's arrival to the building) after it was damaged by one of Leonard's experiments involving rocket fuel, as explained in "The Staircase Implementation", causing everyone to take The Stairs, but it was finally restored around 2019. The building also contains a laundry room in the basement, the layout of which is given to much speculation. Sheldon was once down here to switch the building's power off to suit his own ego before Leonard and Penny. (The Friendship Contraction)

In season 10 Sheldon and Amy moved into Penny's old apartment #4B adding her to the building's occupants. The lease for 4A was in her name.


During the initial production of The Big Bang Theory, Chuck Lorre stated that the set department had built him a stairwell with three walls, and he didn't know what to put on the third wall, which was a problem because it was the most visible. One of his producers suggested that Chuck Lorre put in a broken elevator, which would add to the reason why the characters had to use the stairs.

The only separate sets built for the apartment building (apart from the apartments) are the lobby (ground floor), the laundry room, and the roof. The stairwell is the same set for all shots of the second, third and fourth floors (and the rarely-shown fifth floor), but accessories and details undergo minor changes inside the hallway between each shot filmed to create the illusion that the actors are ascending or descending each floor.


Four at floor of Apartment building

The lobby (first floor)

The laundry room is located here. The main power switch is also in the basement.[1]

First floor (The lobby)
The first floor contains the lobby, which is the entrance to the apartment building. It also contains the mailboxes of the residents who live in the building. This also contains the elevator doors that say out of order, or have the caution tape over them. It's also suggested that the first floor has unseen apartments on it, because this is the floor that housed tenants from whom Leonard bought the couch.[2]

Second floor

  • 2A
    • Mrs. Grossinger lives here, along with her hairless Mexican dog, which Sheldon dislikes.[3] The second floor also has a bicycle in front of the broken elevator door, and a water jug by 2A.
    • Marcus lives here later.[4]
  • 2B
    • Mrs. Petrescu is stated to be the only other known resident on the second floor. It's presumed that she lives in 2B though she is seen in the 2A apartment door.

Third floor

  • 3A
    • Mrs. Gunderson lives here at least in "The Lunar Excitation" (S3E23). There are often flowers on a plant stand by 3A, including poinsettias before Christmas. Judging by the wall behind Mrs. Gunderson, the floor plan of 3A is different from that of Sheldon and Leonard's apartment upstairs.
  • 3B
    • Mrs. Vartabedian also lives on the third floor.[5] Since Mrs. Gunderson lives in apartment 3A then she must live in apartment 3B.

Fourth floor

Sheldon leonard and penny apartment from tbbt

Layout of the fourth floor, including apartments 4A and 4B and the doorways to the unseen apartments 4C and 4D

Fifth floor

  • 5A
    • Alicia (since the "The Dead Hooker Juxtaposition" in 2009, but is likely to have moved out after she landed a big acting job and there has been no mention of her ever since).
  • 5B
    • Here lives Wendell.[6]

There is a three-foot gap to the next building [7], access to the roof and enough room to set up astronomical experiments [8]. This is also where Howard and Bernadette were married. The girls' PROM recreation was also held on the roof.

In case you haven't noticed, the veining in the marble on the elevator walls, and in the light sconces are exactly the same on each floor (they use the same set for each floor during stair-climbing or descending scenes, with only minor differences between each floor).[9].


The earliest version of the apartment building is seen in the episode "The Staircase Implementation".


The first resident of the building that we see in "The Staircase Implementation" is Louie/Louise when Leonard accidentally knocks on the door to his 4B apartment instead of Sheldon's, 4A. We also catch a glimpse of Sheldon's former roommate named "Sebastian" (Steven Yeun) exiting the then functioning elevator, and he warns Leonard about Sheldon. We also know that there is an apartment opening up on the first floor being that Leonard buys the sofa from them for a hundred dollars. As of the fifth season, Sheldon has been living at 2311 No. Los Robles for eight years.

Penny is moving into the building during the Pilot, and Alicia moves into an apartment on the fifth floor during Season 2.

The Elevator[]

In "The Staircase Implementation", we learn that the elevator was working at this time being that Leonard uses it to get to the fourth floor. We also learn that Leonard had miscalculated the formula for an experiment that he was doing with government grade rocket fuel that he was developing. Seeing that the cylinder was about to explode, Leonard attempted to take it out of the building, via the elevator. Sheldon knew that Leonard would not have time, so he pulled Leonard out of the elevator and closed it with the cylinder inside. The cylinder exploded and permanently disabled the elevator. Leonard considers himself being in Sheldon's debt not only for saving his life, but not telling the landlord or the government about what happened. This is the reason why he chooses to keep living with Sheldon.

The elevator is revealed to have finally been fixed after 16 years in "The Change Constant", when Penny is seen stepping through the opening elevator doors after taking it up to the fourth floor, much to Sheldon's consternation.

Where is the apartment building located?[]

The apartment building is located in an entirely fictional location according to Chuck Lorre. He states that the views from the apartment windows were simply pictures of Pasadena taken for the production of the show. Some fans have attempted to pinpoint the exact location of the apartment building, but nothing has been confirmed as accurate. While there is a North Los Robles Avenue in Pasadena that is in close proximity to Pasadena City Hall, and there are several apartment buildings in that general area (albeit none from the angle that either Sheldon or Penny's apartments show), those addresses would be 1 or 2 North Los Robles.  2311 North Los Robles is several miles from City Hall, and is mainly a residential suburban community with no known apartment buildings in the area. Then according to Google Maps, 2311 is at the north end of Los Robles, at the intersection with East Woodbury Road.

Big Bang Theory apartment Building

An actual Google Earth view of the region used in The Countdown Reflection.

Referencing the photo at the top of this page and the speedy zoom at the end of "The Countdown Reflection", the location of the building used to represent the apartment complex for the Google Earth shots is 215 South Madison Avenue, Pasadena, California. A small three-floor apartment building is located at 215 South Madison Avenue; however this building is located six minutes away from North Los Robles Avenue, and therefore does not indicate any real-world connection.

Additional considerations: In the episode when Sheldon tries to learn to drive (the Euclid Alternative) Penny uses Euclid to take him to work at Cal Tech (main address 1200 East California). Leonard always use Los Robles. From the Madison location either would be out of the way. From the Los Robles address Euclid would make no sense as it parallels Los Robles and is a residential street. However Madison is relatively near Colorado Boulevard (the Chevron station) while 2311 North Los Robles is over two miles away.


  • Since the lobby of the building is the first floor and there aren't any apartments on that floor, the building thus has no Apartment 1A and Apartment 1B, as can be seen when people use the stairs and before getting to Apartments 4A and 4B, there are only three floors scene after leaving the lobby instead of four, something quite inaccurate.
  • Since there are sixteen mailboxes (four per floor) seen in the lobby, it would go without saying that in addition to the apartments suffixed with the letters A and B on each floor, there are also apartments suffixed C and D (i.e. 4C and 4D, etc., showing in a layout of the fourth floor above, which has the doors to those apartments on the unseen wall). In a goof that appears in Season 2 episode 1, however, the fourth wall is shown on the security camera view with no doors on the walls.
The security camera view of the 4th wall

security camera view of the 4th wall



  1. according to Penny in "The Friendship Contraction" (S5E15).
  2. mentioned in "The Staircase Implementation" (S3E22)
  3. Mentioned in "The Tangerine Factor" (S1E17)
  4. [[ The Tenant Disassociation]]
  5. Mentioned in "The Vartabedian Conundrum" (S2E10)
  6. The Tenant Disassociation
  7. Mentioned in "The Nerdvana Annihilation" (S1E14)
  8. Shown in "The Lunar Excitation" (S3E23)
  9. Shown in "The Countdown Reflection" (S5E24)