Wealthy families, including the Eatons, moved "up the hill" ca. WWI. The most famous landmark of course is Casa Loma.
It's one of the wealthiest and most prestigious areas in Toronto, yet this area (part of the Casa Loma district officially) has almost no neighborhood identity. I don't think most people know what "South Hill" or "the Hill District" is. The exception is the very small Rathnelly pocket. Some may even say they're in Forest Hill.
A little on the history of the area:
https://scenesto.com/2022/06/15/the-...hill-district/