Q. What is it supposed to be on the show?

A. The home of Summer Roberts (Rachel Bilson) and her father, Dr. Neil Roberts.

Q. Where is it supposed to be on the show?

A. In Newport Beach.

Q. When did we see it on the show?

A. Although Summer appeared on the show from the very first episode, and although we often saw the interior of Summer's bedroom (it's where she & Seth first made love), the outside of the house (a huge mansion) wasn't really shown until the show's third season. But it's hard to forget: an absolutely grand, palatial home.

Summer's mansion first appeared in Episode 3 (of the third season), "The Last Waltz", when Marissa temporarily moved in with Summer (after the Coopers were kicked out of the Nichol mansion, and Julie secretly moved into a trailer park).

After that introduction, the house was seen in almost all of the show's episodes during the third season. We not only saw the front of the house, through frequent establishing shots, but also the pool area and interior as well.

Just about everyone in the cast ends up at Summer's house eventually. Johnny & Chili show up there to invite Marissa to a school dance. Volchok arrives on his motorcycle. Even Anna shows up there, to try to convince Summer that there's nothing between she and Seth. Later in the third season, Julie Cooper (Marissa's mother) takes up with Dr. Roberts (Summer's father), moves into the mansion, and we see all four of them end having awkward meals on the pool patio.

(The estate's tennis court was also used as Dr. Griffin's tennis court in episode 20 of season three, "The Day After Tomorrow".)

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Q. What is it actually in real life?

A. A private home - but not in Newport.

Q. Where can I find it in real life?

A. Most of the mansions in "The O.C." are in Malibu, including the Cohen House, Marissa's house, and the Julie/Caleb mansion. A few others, such as the Model Home and the Suriak rehab center, are located in Palos Verdes.

But to find Summer's house, you'll have to go ten miles north/northeast of Malibu, over the Santa Monica mountains and into the Valley. Yes, unexpectedly, Summer's house is located in the foothills of the southwest San Fernando Valley, in the city of Agoura Hills, to be exact, which lies on the border between Los Angeles and Ventura County

The 7,350 square foot mansion is located off a private road, at 28685 Wagon Road, in Agoura Hills. That's just east/northeast of the intersection of Cornell Road and W. Wagon Road. (Oddly enough, the east end of Wagon Road, a dead-end street, is called "West Wagon Road". Go figure.)

Here is an aerial photo link from Live Local (looking north) and an alternate photo (looking east). Plus a street map link.

If you lived there or were a guest, you would turn east off Cornell Road onto W. Wagon Road, then make a left (north) turn at a private road that leads up to the house. But as you might well expect, this is a gated area, and if you're not a resident or guest, you won't get past the gate at the entrance to West Wagon Road, which blocks your way if you attempt to turn east from Cornell Road. So don't bother to try to drive by to take a look.

The mansion is located far from most other Hollywood sites. The closest attraction listed on my Seeing-Stars site is actually the old Paramount Movie Ranch, which is only one mile southwest of Summer's house. So if you're in the area and frustrated at being unable to see the mansion, at least you'll be able to stop by the movie ranch for some Hollywood sight-seeing.

[Warning: This is a private home. Do not trespass on their property, knock on their door,
or do anything else that might disturb the residents.]

(It's also about 2 miles northeast of the traditionalist Catholic chapel built by Mel Gibson. Which is also private...)

Since you can't drive past, here are a few more photos to give you a better idea of what the mansion looks like:

Q. How the heck did you figure out where it was?

A. I didn't. I assumed that the mansion was most likely in Malibu (or perhaps Palos Verdes), so I had just begun aerial mapping the Malibu area, searching for the home - working my way out from my starting point at Point Dume. It's a very slow process, and it probably would have taken me weeks to eventually find the house (which is on the other side of the mountains from Malibu). But then I got an email from Lennard van Veen, from Holland, who tipped me to the exact location. Lennard says he spent two weeks looking for the mansion, and I must congratulate him on doing a great job of tracking it down. Dank u wel, Lennard!  ;)