Microsoft has added a new theme pack to the Microsoft Store for Windows 10 users. Titled Panoramic Cityscapes PREMIUM, the new theme pack contains 10 high-quality 4K wallpapers, the description of which reads as follows:
Take in the stunning sweep of city lights by day and night. These panoramas span the globe from Sydney to Prague to Singapore to Dubai. This vivid 10-image premium 4k set is free for Windows 10 Themes. These images are to be used as desktop wallpaper only.
After downloading the collection, go to Start > Settings > Personalization > Themes and click on the theme you prefer.
To apply and change to the most appropriate color, based on the current wallpaper, go to Customize > Colors > Automatically select a primary color from the background.