Frankie

This takes place in Foster's Home for Imaginary Friends, located at 1123 Wilson Way. It is a quite literal foster home for imaginary friends until new children adopt them.

Probably the most unique building in the neighborhood, the mansion can easily be spotted, passing through the Gothic gate with "Foster" decorating the upper arc, with a massive willow tree taller than the house itself in the garden, Foster's Home for Imaginary Friends is a very tall Victorian building painted in many shades of dark purple and blue, with tall windows, balconies, and three visible chimneys, two of them tied together. Decorating the very top is a long flag with the Foster's seal on it.

Inside, the mansion is as random and different as it is outside, being very colorful and almost childlike in design, yet at the same time quite regal and Victorian. With big chandeliers, tall staircases, pillars and expensive decoration (including a collection of Madame Foster busts to replace any broken bust in the house). The halls are lined with colorful doors, most of them leading to the rooms where the imaginary friends sleep. The doors don't all quite match, greatly varying in size and shape. The rooms themselves, however, have relatively similar design and furniture, with a few variations. As stated by Madame Foster in "House of Bloo's" and as demonstrated in "Dinner is Swerved", it's fairly easy to get lost inside the confusing halls of Foster's. The mansion also has several trapdoors and secret passages. The mansion has at least six floors and can house up to around 2,000 imaginary friends (exceeding this limit causes excess imaginary friends to have to sleep in out in the hallways or on the foyer floor, as seen in "Emancipation Complication"), though there are normally between 500 and 1,000 friends living in the house at any given time.

Outside the mansion lies a large front yard with various topiaries and hedges with a walkway leading from the ront gate to the front porch. The property line extends significantly past the sides and backyard of the house, allowing for a few smaller, separate buildings and facilities to exist in close proximity of the mansion itself. The exact acreage of the property and square footage of the house itself are unknown, but both measurements seem to rival those of some of the largest residential buildings in the United States, such as the Biltmore Estate, the largest home in the country.

As seen in "Dinner is Swerved," the mansion seems to defy several laws of physics, with the halls and stairways leading to places physically impossible to reach, such as taking several flights of stairs down and still ending up on the highest floor, or falling through trapdoors and ending up on the rooftop. On top of this, the house also appears to be larger on the inside than the outside, with several inconsistent hallway routes and layouts that change with each episode.

There is 19th century speaking tube intercom system wired throughout the house, with several pipes leading to megaphones which can easily carry the voice of whoever is speaking into the microphone throughout the entire mansion. It is mostly used by Mr. Herriman to either make announcements to all of the house's residents at once or to give orders to Frankie no matter where she is in the house.