Gimmelshtump is a town in Drusselstein where Heinz Doofenshmirtz, his family, and his neighbor, Kenny, grew up. It is also the place where Heinz created Balloony. It has been hinted that Dr. Gevaarlijk, Heinz's Evil Science 101 teacher, is also living here. It seems to be a rather poor, semi-rural area, located in Europe. ("Lawn Gnome Beach Party of Terror", "Oil on Candace", "The Chronicles of Meap") It is also where Dr. Phineastein and Ferbgor lived many years ago. Love Händel appeared to have played a concert there too (although this can't be seen as realistic, as they were the same age as in "Dude, We're Getting the Band Back Together" - it was more likely retroactively added by Doofenshmirtz during his flashback). Gimmelshtump life was very negative to Heinz Doofenshmirtz, thus, making him evil. It might have been positive to 2nd dimension Doofenshmirtz, because he only lost his toy train, "Choo-Choo".
Points of interest
See also the image gallery for Drusselstein, the country in which Gimmelshtump lies
Claw Machine District
Young Doofenshmirtz invests his fortune (one three-cent coin) here in an attempt to win his mother's love, but Roger merely adds to his own love bounty ("Make Play").
The Doofenshmirtz household is at least two stories tall and includes some parapets. We learn that before Roger is born, Heinz does have toys to play with. He even seems happy ("Gaming the System").
Gimmelshtump Public Wetness Maker
Not actually a swimming pool, and it only contains water on alternating Thursdays. Doofenshmirtz learns here from his father and all the other kids who pass the high-dive right of passage that he is a schnitzel ("Split Personality").
Gunther Goat Cheese's
Gimmelshtump party palace for kids. Doofenshmirtz reserves a big table there, but no one celebrates with him ("Raging Bully").