Original: Some of the most well-known cities of Southern Ontario are Barrie , Guelph , Hamilton , Kingston , Kitchener , London , St. Catharines-Niagara , Waterloo , and Windsor , and largest among them , Toronto and Ottawa ( also part of the sub-region of Eastern Ontario ) .
Simplified: Some cities in Southern Ontario are Toronto , Ottawa , Barrie , Guelph , Hamilton , Kingston , Kitchener , London , St. Catharines-Niagara , Waterloo , and Windsor .