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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, being that 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, 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 of what to put on the third wall being that 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 (albeit the apartments) are the lobby (ground floor), the laundry room, and the roof. The stairwell is the same set for all shots, but accessories and details are changed inside the hallway between each shot filmed to create the illusion that the actors are ascending or descending each floor.


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

First floor
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, being that this is the floor which housed tenants from whom Leonard bought the couch.

Second floor

  • 2A
    • 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.

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. Seen as Mrs. Gunderson lives in apartment 3A then she must live in apartment 3B.

Fourth floor

  • 4A
    • Sheldon (already lived here in "The Staircase Implementation" in 2003)
    • Leonard (joined Sheldon in "The Staircase Implementation" in 2003)
    • Sebastian (left here in "The Staircase Implementation" in 2003)
    • Penny (joined Leonard in "The Cohabitation Experimentation" in 2016)
    • Rah (briefly in "The Roommate Transmogrification" in 2011; currently joined Leonard and Penny in "The Escape Hatch Identification" in 2017)
  • 4B
    • Penny (Since The Pilot in 2007, left here in "The Cohabitation Experimentation" in 2016)
    • Louie/Louise (already lived here in "The Staircase Implementation" in 2003, and left before The Pilot in 2007)
    • Sheldon (moved here in "The Cohabitation Experimentation" in 2016)
    • Amy (moved here in "The Cohabitation Experimentation" in 2016)

Fifth floor

  • 5A
    • Alicia (since the "The Dead Hooker Juxtaposition" in 2009).

There is a 3 foot gap to the next building, access to the roof and enough room to set up astronomical experiments. This is also the location that Howard and Bernadette were married

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.


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 episode, 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.

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The Big Bang TheoryYoung SheldonVideo
Main Characters: Leonard HofstadterSheldon CooperPenny HofstadterHoward WolowitzRajesh KoothrappaliAmy Farrah FowlerBernadette Rostenkowski-WolowitzStuart BloomEmily SweeneyLeslie Winkle

Recurring Characters: Barry KripkeWil WheatonAltheaKurtEric GablehauserMary CooperDebbie WolowitzV.M. KoothrappaliMrs. KoothrappaliMikeStephanie BarnettBeverley HofstadterPresident SiebertZack JohnsonPriya KoothrappaliWyattMike RostenkowskiMrs. RostenkowskiAlex JensenJanine DavisLucyProfessor ProtonDavid GibbsClaireStephen HawkingAlfred HofstadterColonel Richard WilliamsDenise
Minor Characters: ChristyLalita GuptaToby LoobenfeldDennis KimDimitriMissy CooperBlainTomOctaviaMariaLourdesRamona NowitzkiKathy O'BrianDavid UnderhillAliciaMikaylaCaptain SweatpantsLonely LarryDr. CrawleyBethanySarahSkeeterProfessor LaughlinAbbyMarthaOfficer HackettSandyGlenVenkatesh KoothrappaliSebastianLouie/LouiseJoyce KimMrs. GundersonJoyMrs. FowlerAngela PageProfessor GlennMrs. LathamTodd ZarneckiSusanRandallColonel Richard Williams

Season 1: PilotThe Big Bran HypothesisThe Fuzzy Boots CorollaryThe Luminous Fish EffectThe Hamburger PostulateThe Middle-Earth ParadigmThe Dumpling ParadoxThe Grasshopper ExperimentThe Cooper-Hofstadter PolarizationThe Loobenfeld DecayThe Pancake Batter AnomalyThe Jerusalem DualityThe Bat Jar ConjectureThe Nerdvana AnnihilationThe Porkchop IndeterminacyThe Peanut ReactionThe Tangerine Factor

Season 2: The Bad Fish ParadigmThe Codpiece TopologyThe Barbarian SublimationThe Griffin EquivalencyThe Euclid AlternativeThe Cooper-Nowitzki TheoremThe Panty Piñata PolarizationThe Lizard-Spock ExpansionThe White Asparagus TriangulationThe Vartabedian ConundrumThe Bath Item Gift HypothesisThe Killer Robot InstabilityThe Friendship AlgorithmThe Financial PermeabilityThe Maternal CapacitanceThe Cushion SaturationThe Terminator DecouplingThe Work Song NanoclusterThe Dead Hooker JuxtapositionThe Hofstadter IsotopeThe Vegas RenormalizationThe Classified Materials TurbulenceThe Monopolar Expedition
Season 3: The Electric Can Opener FluctuationThe Jiminy ConjectureThe Gothowitz DeviationThe Pirate SolutionThe Creepy Candy Coating CorollaryThe Cornhusker VortexThe Guitarist AmplificationThe Adhesive Duck DeficiencyThe Vengeance FormulationThe Gorilla ExperimentThe Maternal CongruenceThe Psychic VortexThe Bozeman ReactionThe Einstein ApproximationThe Large Hadron CollisionThe Excelsior AcquisitionThe Precious FragmentationThe Pants AlternativeThe Wheaton RecurrenceThe Spaghetti CatalystThe Plimpton StimulationThe Staircase ImplementationThe Lunar Excitation
Season 4: The Robotic ManipulationThe Cruciferous Vegetable AmplificationThe Zazzy SubstitutionThe Hot Troll DeviationThe Desperation EmanationThe Irish Pub FormulationThe Apology InsufficiencyThe 21-Second ExcitationThe Boyfriend ComplexityThe Alien Parasite HypothesisThe Justice League RecombinationThe Bus Pants UtilizationThe Love Car DisplacementThe Thespian CatalystThe Benefactor FactorThe Cohabitation FormulationThe Toast DerivationThe Prestidigitation ApproximationThe Zarnecki IncursionThe Herb Garden GerminationThe Agreement DissectionThe Wildebeest ImplementationThe Engagement ReactionThe Roommate Transmogrification
Season 5: The Skank Reflex AnalysisThe Infestation HypothesisThe Pulled Groin ExtrapolationThe Wiggly Finger CatalystThe Russian Rocket ReactionThe Rhinitis RevelationThe Good Guy FluctuationThe Isolation PermutationThe Ornithophobia DiffusionThe Flaming Spittoon AcquisitionThe Speckerman RecurrenceThe Shiny Trinket ManeuverThe Recombination HypothesisThe Beta Test InitiationThe Friendship ContractionThe Vacation SolutionThe Rothman DisintegrationThe Werewolf TransformationThe Weekend VortexThe Transporter MalfunctionThe Hawking ExcitationThe Stag ConvergenceThe Launch AccelerationThe Countdown Reflection
Season 6: The Date Night VariableThe Decoupling FluctuationThe Higgs Boson ObservationThe Re-Entry MinimizationThe Holographic ExcitationThe Extract ObliterationThe Habitation ConfigurationThe 43 PeculiarityThe Parking Lot EscalationThe Fish Guts DisplacementThe Santa SimulationThe Egg Salad EquivalencyThe Bakersfield ExpeditionThe Cooper/Kripke InversionThe Spoiler Alert SegmentationThe Tangible Affection ProofThe Monster IsolationThe Contractual Obligation ImplementationThe Closet ReconfigurationThe Tenure TurbulenceThe Closure AlternativeThe Proton ResurgenceThe Love Spell PotentialThe Bon Voyage Reaction
Season 7: The Hofstadter InsufficiencyThe Deception VerificationThe Scavenger VortexThe Raiders MinimizationThe Workplace ProximityThe Romance ResonanceThe Proton DisplacementThe Itchy Brain SimulationThe Thanksgiving DecouplingThe Discovery DissipationThe Cooper ExtractionThe Hesitation RamificationThe Occupation RecalibrationThe Convention ConundrumThe Locomotive ManipulationThe Table PolarizationThe Friendship TurbulenceThe Mommy ObservationThe Indecision AmalgamationThe Relationship DiremptionThe Anything Can Happen RecurrenceThe Proton TransmogrificationThe Gorilla DissolutionThe Status Quo Combustion
Season 8: The Locomotion InterruptionThe Junior Professor SolutionThe First Pitch InsufficiencyThe Hook-up ReverberationThe Focus AttenuationThe Expedition ApproximationThe Misinterpretation AgitationThe Prom EquivalencyThe Septum DeviationThe Champagne ReflectionThe Clean Room InfiltrationThe Space Probe DisintegrationThe Anxiety OptimizationThe Troll ManifestationThe Comic Book Store RegenerationThe Intimacy AccelerationThe Colonization ApplicationThe Leftover ThermalizationThe Skywalker IncursionThe Fortification ImplementationThe Communication DeteriorationThe Graduation TransmissionThe Maternal CombustionThe Commitment Determination
Season 9: The Matrimony MomentumThe Separation OscillationThe Bachelor Party CorrosionThe 2003 ApproximationThe Perspiration ImplementationThe Helium InsufficiencyThe Spock ResonanceThe Mystery Date ObservationThe Platonic PermutationThe Earworm ReverberationThe Opening Night ExcitationThe Sales Call SublimationThe Empathy OptimizationThe Meemaw MaterializationThe Valentino SubmergenceThe Positive Negative ReactionThe Celebration ExperimentationThe Application DeteriorationThe Solder Excursion DiversionThe Big Bear PrecipitationThe Viewing Party CombustionThe Fermentation BifurcationThe Line Substitution SolutionThe Convergence-Convergence
Season 10: The Conjugal ConjectureThe Military MiniaturizationThe Dependence TranscendenceThe Cohabitation ExperimentationThe Hot Tub ContaminationThe Fetal Kick CatalystThe Veracity ElasticityThe Brain Bowl IncubationThe Geology ElevationThe Property Division CollisionThe Birthday SynchronicityThe Holiday SummationThe Romance RecalibrationThe Emotion Detection AutomationThe Locomotion ReverberationThe Allowance EvaporationThe Comic-Con ConundrumThe Escape Hatch IdentificationThe Collaboration FluctuationThe Recollection DissipationThe Separation AgitationThe Cognition RegenerationThe Gyroscopic CollapseThe Long Distance Dissonance
Season 11: The Proposal ProposalThe Retraction ReactionThe Relaxation IntegrationThe Explosion ImplosionThe Collaboration ContaminationThe Proton RegenerationThe Geology MethodologyThe Tesla RecoilThe Bitcoin EntanglementThe Confidence ErosionThe Celebration ReverberationThe Matrimonial MetricThe Solo OscillationThe Separation TriangulationThe Novelization CorrelationThe Neonatal NomenclatureThe Athenaeum AllocationThe Gates ExcitationThe Tenant DisassociationThe Reclusive PotentialThe Comet PolarizationThe Monetary InsufficiencyThe Sibling RealignmentThe Bow Tie Asymmetry
Season 12: The Conjugal ConfigurationThe Wedding Gift WormholeThe Procreation CalculationThe Tam TurbulenceThe Planetarium CollisionThe Imitation PerturbationThe Grant Allocation DerivationThe Consummation DeviationThe Citation NegationThe VCR IlluminationThe Paintball ScatteringThe Propagation PropositionThe Confirmation PolarizationThe Meteorite ManifestationThe Donation OscillationThe D & D VortexThe Conference ValuationThe Laureate AccumulationThe Inspiration DeprivationThe Decision ReverberationThe Plagiarism SchismThe Maternal ConclusionThe Change ConstantThe Stockholm Syndrome

The Apartment BuildingApartment 4AApartment 4BThe ElevatorCalifornia Institute of TechnologyWolowitz HouseThe Comic Center of PasadenaPasadenaThe Cheesecake FactoryRaj's ApartmentAmy's ApartmentHoward and Bernadette's ApartmentThe StairsSheldon's Old OfficeRaj's Old OfficeSheldon's New OfficeHoward's LabThe University CafeteriaKripke's Plasma LabInternational Space StationThe Kinetics Lab
See Also
Unaired Pilot