Professor Utonium and The Powerpuff Girls both live within the same building, often referred to as, just, ' 'The House', throughout the series. Inside are many room each with unique purposes.
Main Rooms in the Series
Bathroom - The girl's bathroom is all white, with a toilet, 3 sinks, and claw-foot bathtub big enough for all 3 girls plus many more. There are towels hanging on the wall; you guessed it-pink, blue and green ones, and a plush purple rug in front of the door. Buttercup hates bathtime, but Blossom and Bubbles embrace it.
The Kitchen - The kitchen is as modern as the rest of the house; with dark cabinets, stainless steel appliances, and a booth table, where the Professor is often seen making liver and onions for the girls, to their disgust.
The Girl's Bedroom - The girl's bedroom is featured in almost every episode. The bed has a comforter with pink, green, and blue sections for each girl to sleep in. There are many pink decorations and tons of pink furniture. It has entire decoration on the bed’s headboards: a large pink heart with the initials “PPG” inside it. The three circular windows are in their room. The hot phone, which is connected to Mayor in City Hall, is sitting on a table in the bedroom. He calls the girls mostly when they are getting ready for bed, which agitates them. The room is covered in stuffed animals and toys, also.
The Living Room - It is also modern, with a retro cubed fireplace, plank stairs, and futuristic furniture. This area is used in parties, and is also a source of amusement for the girls.
Professor Utonium's Lab - Where Utonium spends most of his time. Lots of chemicals, test tubes, and cabinets, and most importantly the birthplace of The Powerpuff Girls.
Training Room - A hard light hologram based simulation room, where the girls fight monsters for practice. These simulations range on a danger setting from 1(easiest) to 11(hardest).
The exterior model of the house is based off of the design of the villa in the 1958 foreign film "Mon Oncle." This is confirmed in the director's commentary on The Powerpuff Girls Movie DVD special features.
The house's interior changed for the release of The Powerpuff Girls Movie and remained different for the remainder of the series. In the first 3 seasons, it has a more compact internal appearance with several hallways throughout. After the release of the film, the foyer/living room was given a high ceiling, and the home was more connected, spacious, cubic, and open.
The three pink, green, and blue stripes on the Girls' bed tend to swap places in episodes.
The Training room is similar to the "Danger Room" from the X-Men franchise.
The house was redesigned completely in the reboot.