The South Hill neighbourhood is defined by the Avenue Road Hill. This historic land formation was the former shoreline of ancient Lake Iroquois, whose chilly waters receded into present day Lake Ontario some 12,000 years ago at the end of the last ice age.

The escarpment that Lake Iroquois left behind was covered by a dense forest interrupted only by the ponds, creeks, and waterfalls that graced the Avenue Road Hill up until the 1900's.

South Hill's natural beauty made it an instant favourite with wealthy Toronto landowners. In the mid to late 1800's, South Hill was dotted with mansions that were unsurpassed in variety and scope anywhere else in Toronto. "Oaklands", the gingerbread mansion overlooking Avenue Road, "Spadina House" at 285 Spadina Road and "Casa Loma", the 98 room dream home of Sir Henry William Pellatt, still endure from this bygone era.