In pictures: The world's tallest observation decks

Canton Tower.

10. International Commerce Centre in Hong Kong, China. Building height: 484m. Observation deck: 388m. Courtesy Wilson Ling

2. Shanghai World Financial Centre in Shanghai, China. Building height: 492m. Observation deck: 474m. Courtesy Thierry Beauvier

3. Burj Khalifa in Dubai, United Arab Emirates. Building height: 828m. Observation deck: 452m. Courtesy Axel Schmies

4. Tokyo Sky Tree in Tokyo, Japan. Building height: 634m. Observation deck: 450m. Courtesy Mokurenmei

5. CN Tower in Toronto, Canada. Building height: 553m. Observation deck: 447m. Courtesy Edvard Mahnic

6. KK100 in Shenzhen, China. Building height: 442m. Observation deck: 427m. Courtesy ArnieLee

7. Guangzhou International Finance Centre in Guangzhou, China. Building height: 438m. Observation deck: 415m. Courtesy Wylie Poon

8. Willis Tower in Chicago, USA. Building height: 412m. Observation deck: 413m. Courtesy Skydeck Chicago

9. Taipei 101 in Taipei, Taiwan. Building height: 509m. Observation deck: 392m. Courtesy Daniel Shih