The Canton tower in Guangzhou is (currently) the 5th tallest structure in the world. You can (after suitable payment) take a lift to a viewing platform and gain access to some amazing views. Fortunately when I went it was a pretty good day – Guangzhou is usually much hazier than this.
You can pay extra to go to the very top, which is outside on the roof. In retrospect it’s not worth the money as it’s only another couple of floors higher. It doesn’t help that they advertise the cheaper price as ‘halfway’.
At the top is a bizarre bubble ride around the edge of the roof and, if you’re so inclined, a bungee jump from the tower mast.