What is the talk mainly about?

Toronto, in the province of Ontario, is one of the largest and busiest cities in Canada. One of the reasons for its dynamism has been the success of its downtown area.(95)This area incorporates a massive underground complex, linking the subway system with underground passages and shopping arcades,(96)which in turn connect with a convention center and hotels. This urban concept is particularly appropriate because of the severe fluctuations in weather which Toronto experiences.(97)Annually, temperatures can vary by as much as 40 degrees. The underground zone ensures that the climate does not prevent people from gathering in the city center.(96)Small and medium sized businesses have remained in the city rather than moving to the suburbs. The life has not drained out of the city, ensuring that Toronto is a memorable place to visit.