Apartment 4B is Penny's apartment and the secondary setting for the Big Bang Theory. It is located on the fourth floor of the Building at 2311 N. Los Robles Avenue, Pasadena, California. When viewed from the satellite photographics in The Countdown Reflection episode it appears to be located at 215 S Madison Ave. It is most well known as being located directly across the hallway from Apartment 4A, which is the apartment that Sheldon and Leonard live in.
4B is a smaller apartment than its counterpart across the hall, having only a single bedroom instead of two. However, like its counterpart across the hall, it has an open floor plan where the living room and the kitchen are part of the same room. Also like 4A, the apartment is entered into the living room through the hallway. The right wall has a single door that leads into Penny's bedroom. Continuing along the wall is a large window with her kitchen table by it. The bathroom in the apartment is located through her bedroom, and is the only way to access the bathroom.The wall on the left immediately after you enter the apartment is not visible, as it is the view into the apartment when episodes are being filmed. But the wall houses Penny's TV and entertainment center, and ends at the kitchen area.
In Penny's kitchen, there is an island with chairs as well as a small window over the sink.
History EditApartment 4B is first seen in the pilot, upon meeting Penny, who is the newest tenant in the building. We also find out that the former occupant of 4B was "a 200 pound transvestite with a skin condition". This former occupant's name was revealed as Louie/Louise in the following episode called The Big Bran Hypothesis. The Big Bran Hypothesis also gives us the first view inside the apartment, in which Sheldon and Leonard help move in a media set while Penny is at work. Sheldon describes Louie/Louise as being cleaner than Penny, having helped him run cable for a web-cam while he lived there.
Note: When Leonard first sees Penny through the doorway in the Pilot, the kitchen should be visible, but is not. Only the coffee table that is still in front of her counch can still be seen in her apartment set.