For 12 years (and seasons), fans of The Big Bang Theory were gifted with the friendships and relationships of Sheldon, Leonard, Penny, Howard, Raj, Bernadette, and Amy. Episode after episode, we've seen this group walk up and down that apartment staircase, knock three times on those apartment doors, and sit night after night in apartment 4A's living room to enjoy take-out and conversation. Most of the significant moments in these characters' lives happened in this apartment, which is ironic considering Sheldon never wanted people over in the first place.
Although Big Bang Theory diehard fans have seen these episodes time and time again, there are still new things that pop out every time we watch. When it comes to Sheldon and Leonard's apartment (now Leonard and Penny's), we found 10 small details about apartment 4A—and the building that it's in—that the average fan never knew.
THE REAL ADDRESS IS IN THE MIDDLE OF AN INTERSECTION
In the episode "The Desperation Emanation," Sheldon says the address of their apartment is 2311 North Los Robles Avenue in Pasadena, California. However, when you look that address up on Google Maps, it comes up smack dab in the middle between Los Robles Ave. and East Woodbury Rd.
However, in the episode where Leonard lies to Sheldon about going across the street to use the gas station bathroom, they note that their building is near Los Robles Ave. and Colorado.
THE ADDRESS SEEMED TO CHANGE
On the day Bernadette and Howard were to be married, they chose a quickie wedding on the rooftop of Sheldon and Leonard's apartment (mainly because they wanted their wedding caught by a floating satellite).
It's in this episode where they say their apartment building's address is 215 South Madison Avenue. If you look up the address on maps, there's an actual apartment building here. However, it's a 10-minute drive from the other address.
APARTMENT 4A MAY HAVE A SECRET MEANING
The Big Bang Theory is known for throwing Easter eggs in each episode; whether it's through clothing, word choices or name drops. That being said, do you think their apartment room also has a secret meaning to it?
According to the show's Fandom page, when you say 4A it sounds like you're saying foray. Foray could mean the actual definition, which is raiding an enemy's territory or it could be a special shoutout to June Foray, the voice of Rocky the Flying Squirrel.
THERE WAS A REASON SHELDON GOT RID OF THOSE GLOW-IN-THE-DARK ARROWS
When Leonard starts spending more time with Penny, Sheldon decides to help Raj out and have him take Leonard's room while he's out. As he's giving Raj the rundown of the apartment (and an extensive contractual agreement) in season four, he shows Raj the glow-in-the-dark arrows on the apartment's floors, directing all individuals to the emergency exit.
However, later in season five, the arrows are nowhere to be found. Where did they go? Well, if you listen closely in the 15th episode ("The Friendship Contraction"), Sheldon explains he got rid of them because of how carcinogenic they were.
KEEP YOUR EYES PEELED IN THE LAUNDRY ROOM
Every Saturday night at 8:15pm, Sheldon does his laundry in the apartment building's laundry room in the basement. Saturday is a great time to do laundry because everyone typically has plans — but not our Shelly.
And while Sheldon would never dream of taking his clothes off in public (especially a communal laundry room), there's a sign hanging in the laundry room that says "Please keep your clothes on while doing laundry." If Sheldon isn't the only one with strange habits, then who in their building is getting naked when they shouldn't be?! And an even better question, who caught them?
SHELDON TAKES THE APARTMENT FLAG SERIOUSLY
We first learn about Sheldon and Leonard's official apartment flag when Sheldon is giving Leonard the official roommate agreement. Sheldon loves flags so much that he continues this theme when filming his "hit" Internet show, Fun With Flags.
Sheldon explains that when the apartment is in distress the flag will be turned upside down, signifying so. Similar to having the flag up at half-mast. Well, if you look closely when Sheldon and Leonard are going through tough times, the roommate flag magnet is typically turned upside down on the fridge.
A SPECIAL SHOUTOUT
Carol Ann Susi was the iconic, boisterous voice behind Howard's mother. Sadly, Carol passed away suddenly in 2014 of cancer. Knowing the show could never duplicate Susi, they had Howard's mother pass away on the show as well.
To honor Carol, there is a small picture of her hanging on Leonard and Sheldon's fridge. It's so small that it's a blink-and-you'll-miss-it kind of thing. And since fans never saw Howard's mother's face before, her picture isn't something that would catch most fans' eyes.
THERE ARE UNSEEN APARTMENTS IN THE APARTMENT LOBBY
According to The Big Bang Theory's Fandom page, it's quite possible that there were apartments in the main lobby — we've just never seen them. When it comes to the lobby, we see the front doors, the staircase, the broken elevator, and the mailboxes. So, it's safe to say there is a hall behind that green door that has at least two apartments in it.
Following that point, when Leonard is describing the moment he moved into Sheldon's and finally bought furniture, he said that he bought their couch off the tenants who were moving from the first floor.
THE GANG ISN'T ACTUALLY WALKING UP FOUR FLOORS
In case you were wondering if The Big Bang Theory production crew made the cast walk up four flights of stairs in every single episode, they didn't. Creating floor after floor would have been harder for production to film. Instead, we see the two staircases, the two apartments, and the elevator door.
To make each floor look different than the next, they someones added a plant or a caution sign — small differences to make it look like these characters were actually walking up and down from their apartment.
WHY DOES EVERYONE KNOCK?
As we know, Sheldon knocks on every door three times to give the person on the other side of the door an ample amount of time to get their pants on before opening the door. But if you take a harder look, each apartment actually has a doorbell right next to the door.
Why does Sheldon continue to knock on Penny's door (which is right across from apartment 4A) when she has a doorbell? Likewise, why do Penny, Raj, and Howard knock on apartment 4A's door when they too have a doorbell? Is this all for Sheldon? We'll never know.