The apartment building, or simply the building, refers to the apartment building at 2311 North Los Robles Avenue, Pasadena, California. When viewed from the satellite photographs in "The Countdown Reflection" episode it appears to be 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). The Elevator has been broken for several years (predating the beginning of the series), 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. The building also contains a laundry room in the basement.
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.
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.
- Mrs. Grossinger lives here, along with her hairless Mexican dog, which Sheldon dislikes. The second floor also has a bicycle in front of the broken elevator door, and a water jug by 2A.
- Mrs. Petrescu is stated to be the only other known resident on the second floor. It's presumed that she lives in 2B.
- Mrs. Vartabedian also lives on the third floor. Since Mrs. Gunderson lives in apartment 3A then she must live in apartment 3B.
- Sheldon (already lived here in "The Staircase Implementation" in 2003 until October 2016)
- Leonard (joined Sheldon in "The Staircase Implementation" in 2003)
- Penny (began staying here off-and-on after getting married to Leonard, moved here permanently in October 2016)
- Sebastian (left here in "The Staircase Implementation" in 2003)
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)..
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.
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.
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.
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.), but the doors to those apartments are never shown because they are on the hallway wall that serves as the view into the hallway on each floor which shows the stairwell and the elevator.
- ↑ according to Penny in "The Friendship Contraction" (S5E15).
- ↑ mentioned in "The Staircase Implementation" (S3E22)
- ↑ Mentioned in "The Tangerine Factor" (S1E17)
- ↑ Mentioned in "The Vartabedian Conundrum" (S2E10)
- ↑ Mentioned in "The Nerdvana Annihilation" (S1E14)
- ↑ Shown in "The Lunar Excitation" (S3E23)
- ↑ Shown in "The Countdown Reflection" (S5E24)