What is the tallest structure in the Western Hemisphere?
The CN Tower in Toronto, Ontario, Canada is the tallest free-standing structure in the Western Hemisphere. It was completed in 1976, and was the tallest structure in the world from 1975 until 2007, when it was surpassed by the Burj Khalifa.
Below is an instruction that describes a task, paired with an input that provides further context. Write a response that appropriately completes the request.
### Instruction: What is the tallest structure in the Western Hemisphere?
### Input: 
### Response: The CN Tower in Toronto, Ontario, Canada is the tallest free-standing structure in the Western Hemisphere. It was completed in 1976, and was the tallest structure in the world from 1975 until 2007, when it was surpassed by the Burj Khalifa.