Fort William/Port Arthur/Thunder Bay/Lakehead, 103,000 to 131,000 depending on how and what you count.
Port Arthur, 46,000 ©
rocket1964
Fort William, 50,000 ©
rocket1964
Current River, 4,000 ©
Geekent
Academy Heights/Lakehead University and College Heights, neighbourhoods of Port Arthur, also have skylines (2 or more tall buildings near each other) but there are no real vantage points for them so I don't have any pictures.
Kenora, 15,000:
Some aerial photos of apartment blocks and downtown ©
Ricky Wilkinson
Best Western Kenora, tallest hotel between Ottawa and Winnipeg. ©
Scienceduck