Photo credits

Background photos from Wikimedia Commons, used under their free licences.

New York: Manhattan at night.jpg by Bruno_53, CC BY 2.0 (resized)
Singapore: City of Lights (Singapore).jpg by Zexsen Xie, CC BY 2.0 (resized)
Dubai: Downtown, Dubai (36714617205).jpg by Pixabay user bulletrain743, CC0
Tokyo: Tokyo Tower, Minato City.jpg by David Kernan, CC BY 4.0 (resized)
Shanghai: Pudong Shanghai November 2017.jpg by King of Hearts, CC BY-SA 4.0 (resized)
London: City of London from Waterloo Bridge (16170605850).jpg by Aleem Yousaf, CC BY-SA 2.0 (resized)

Hong Kong background: HUNTOM Ltd.