Most of the action in this movie takes place around the two houses you see below:
the Delta Psi Beta frat house (on the left), and the Radner's family home (on the right):
...as war breaks out between an easy-going couple, 'Mac' & 'Kelly' (Seth Rogen & Rose Byrne),
and the Delta Psi Beta fraternity, led 'Teddy' (Zac Efron).
In real life, the "frat house" is located at 2203 W. 20th Street, in Central Los Angeles.
And the family home, next door, is at 2179 W. 20th Street.
The 'frat house' is NOT a frat house, in real life. It's a 4-bedroom historic home built in 1907.
The family home next door is actually the larger of the two, with 5 bedrooms, and was built in 1903.
Both houses are on the north side of 20th Street, between S. Gramercy Place and S. Western Ave,
just north of the Santa Monica (10) Freeway, and one street south of Washington Blvd.
Hollywood likes these nice, old picturesque homes, the kind found in the nearby
West Adams district, and uses them fairly often in their productions.
Here is a Google StreetView of the two homes.
[ Warning: these are private homes. Do not trespass on their property,
knock on their doors, or do anything else that might disturb the residents. ]
( The neighborhood is listed by the L.A. Times as Harvard Heights, and is described by the
Times as a low income/high crime area - so exercise reasonable caution. )
The screencap below comes from the film's raunchy, R-rated Red Band trailer. Obviously, this is not the same
frat house, but since the Greek letters identify it as Delta Psi Beta, it would seem to be a flashback
to the frat's earlier party antics, that resulted in them burning down their previous frat house.
( I don't honestly remember seeing this scene in the movie
- perhaps they cut the scene, or maybe I just blinked & missed it.)
Whatever, that former "frat house" (with the Greek columns) is located at 2218 S. Harvard Blvd,
in Central Los Angeles, about half a mile southwest of the main houses, on the west side
of Harvard Blvd, just south of the Santa Monica (10) Freeway.
Built in 1910, and known as the Beckett Residence (an L.A. Historic-Cultural Monument),
this now-uninhabitable home is used often in movies. It was seen in the 2011
romantic comedy, "No Strings Attached", as yet another frat house, where
Ashton Kutcher and Natalie Portman's characters met at a party.
Here is a Google StreetView of the house.
The most publicized gag in the movie takes place at Mac's (Seth Rogen) office,
when the frat steals his car's airbags and plants one on his office chair...
...sending him crashing through the ceiling:
Here is a Google StreetView of the office park's entrance.
This scene was shot inside an office building at
20525 Nordhoff Street, in Chatsworth, CA.
(That's in the northwest corner of the San Fernando Valley,
almost 30 miles northwest of the two homes.)
The scenes where Mac & Kelly take their baby to the park
were filmed about 5 miles northeast of the two homes...
at Bellevue Park, at 826 Lucile Avenue, in the Silver Lake district of Los Angeles,
Here is a Google StreetView of the park.
between Sunset Blvd and the Hollywood Freeway.
There is a scene where Teddy (Zac Efron) meets with his friend 'Pete' at a
Student Jobs Fair, supposedly at Braxton University, and is told
by a corporate recruiter that he's "too dumb" for a job.
That scene was actually filmed on the campus of Los Angeles City College,
at 855 N Vermont Avenue, in Los Angeles.
(That's just a mile east of Bellevue Park.)
The new LACC Student Union can be seen in the background of that scene:
Here is a Google StreetView of the campus.
In an attempt to get Delta Psi Beta expelled from campus, Mac & Kelly meet with a
mistreated pledge of the frat (nicknamed "Assjuice"), in a 50's diner, and attempt
to turn him against the frat by reminding him of how he has been abused.
They want him to wear a pair of spy glasses and video record
Teddy hazing him, so they can report him to the Dean.
When the kid is reluctant to do it, they offer him $1,000 cash. He takes it.
That scene was filmed inside the Johnny Rockets restaurant, at
the Universal CityWalk, next to Universal Studios Hollywood.
It's located between Tony Roma's and Jamba Juice, in the main CityWalk
(circular) plaza ("Fountain Court"), under that dome-like geodesic roof.
(You can't miss it. It's the one with the giant neon hamburger & fries on the roof.)
The scenes of Mac handing out flyers to homeless people & hookers, advertising
a free party at the Delta Psi Beta house, were shot at two nearby locations:
The short scene where Mac hands out the flyers to the homeless under a bridge, was filmed
under the Hollywood Freeway overpass at Heliotrope Drive & Clinton Street.
That's about four miles northeast of the two main houses.
Here is a Google StreetView of that overpass.
The latter scene, where he hands out flyers to the hookers on a corner, was shot
on the street outside 4350 Melrose Avenue - at the corner of Heliotrope.
(The camera is looking west, down the south side of Melrose.)
That's just a block north of the overpass where they faked the homeless camp.
Here is a Google StreetView of that corner.
Four months after the final party, Mac comes across Teddy working as
a shirtless male model outside of an Abercrombie & Fitch store.
They talk about how his life has been going, and then Mac (Seth) joins
him by taking his own shirt off for some silly mugging:
That scene was shot outside a real Abercrombie & Fitch store
on the Universal CityWalk, next to Universal Studios Hollywood.
In fact, it's located right across the Fountain Court plaza from the Johnny Rockets
where they filmed the interior scene of Mac talking to "Assjuice".
(Look closely, and you can glimpse that Johnny Rockets
behind Mac as he spots Teddy outside the store.)
Here's a map of CityWalk showing both stores' locations:
Here is a Google StreetView of that A&F store on CityWalk.