Video 21

Information Sources:

https://en.wikipedia.org/wiki/History_of_the_world's_tallest_buildings
https://www.emporis.com/statistics/history-of-worlds-tallest-buildings

Images Credit:

1. Burj Khalifa
https://skyscrapercenter.com/building/burj-khalifa/3
https://citycarddubai.com/portfolio/go-forward-applications/
http://dubaitoptours.com/m/tour/18

2. Taipei 101
https://skyscrapercenter.com/building/taipei-101/117
http://pcwallart.com/taipei-101-wallpaper-4.html
https://dilemma-x.net/2012/04/01/%EF%BB%BFone-world-trade-center-in-new-york-rises-to-the-104th-floor/taipei-101/
http://wallpaperswide.com/taipei_101-wallpapers.html

3. Petronas Towers
https://skyscrapercenter.com/building/petronas-twin-tower-1/149
http://www.independent.co.uk/travel/asia/kuala-lumpur-how-the-malaysian-capital-is-raising-its-game-with-innovative-new-restaurants-and-10290978.html
http://fareastadventuretravel.com/travel-ideas/petronas-twin-towers-kl-malaysias-star-attraction-tour/
http://1920x1080hdwallpapers.com/city/petronas-towers-kuala-lumpur/

4. Willis Tower
https://skyscrapercenter.com/building/willis-tower/169
http://www.vosizneias.com/197756/2015/03/16/chicago-il-report-blackstone-buying-chicagos-willis-tower-for-1-3-billion/
https://en.wikipedia.org/wiki/File:Willis_Tower_night_2.jpg
http://popular-destination.blogspot.co.id/2015/07/willis-tower-of-chicago-usa.html

5. World Trade Center
https://www.skyscrapercenter.com/building/one-world-trade-center/200
http://www.zryxsw.com/world-trade-center-wallpaper/1221379.html
http://www.zryxsw.com/world-trade-center-wallpaper/1221565.html
http://letsrollforums.com//world-trade-center-night-t25248.html?s=17afb8013d351b69b26065403e01b538&p=222976

6. Empire State Building
https://skyscrapercenter.com/building/empire-state-building/261
http://fineartamerica.com/featured/old-fashioned-empire-state-building-alex-ag.html
http://vizts.com/empire-state-building/
http://www.history.com/news/history-lists/10-surprising-facts-about-the-empire-state-building

7. Chrysler Building
https://skyscrapercenter.com/building/chrysler-building/422
https://500px.com/photo/137071739/chrysler-building-aerial-sunset-by-toby-harriman
https://en.wikipedia.org/wiki/File:Chrysler_Building_Midtown_Manhattan_New_York_City_1932.jpg
http://nyss.one/project4.html

8. Bank of Manhattan Trust Building (The Trump Building)
https://skyscrapercenter.com/building/the-trump-building/619
https://en.wikipedia.org/wiki/File:40_Wall_Street_Manhattan_New_York_City.jpg
http://www.mrakodrapy.com/2012/02/bank-of-manhattan-trust-building.html

9. Woolworth Building
https://skyscrapercenter.com/building/woolworth-building/969
https://en.wikipedia.org/wiki/File:View_of_Woolworth_Building_fixed_crop.jpg
http://thearch.nyc/2015/10/building-in-the-spotlight-the-woolworth/
https://www.flickr.com/photos/sunnydazzled/8640717310

10. Metropolitan Life Tower
https://skyscrapercenter.com/building/metropolitan-life-tower/1383
https://en.wikipedia.org/wiki/File:Met_life_tower_crop.jpg
https://rolands.photos/Travel/New%20York/Midtown/index.html
http://appv1.lumenpulse.com/en/project/162/new-york-edition-hotel

11. Singer Building
https://skyscrapercenter.com/building/singer-building/2080
https://en.wikipedia.org/wiki/File:SingerBuilding_crop.jpg
https://en.wikipedia.org/wiki/File:Singer_City_Investing_Hudson_Terminal_1909_crop.jpg
http://untappedcities.com/2013/08/13/cities-101-how-do-you-demolish-a-skyscraper/
http://skyscraperpage.com/forum/showthread.php?t=171830&page=3

12. Philadelphia City Hall
https://skyscrapercenter.com/building/philadelphia-city-hall/2958
https://en.wikipedia.org/wiki/File:City_Hall_Philadelphia.jpg
https://commons.wikimedia.org/wiki/File:Philadelphia_City_Hall_7.jpg
https://commons.wikimedia.org/wiki/File:CITY_HALL_PHILADELPHIA.jpg