1) The eye of a cyclone is a region of calm, relatively clear skies and light winds at the center of the storm.

2) The concept of self-driving cars, or autonomous vehicles, is being actively developed by companies such as Tesla, Google (Waymo), and Uber.

3) The musical "Les Misérables" is one of the longest-running shows in the West End and Broadway, with over 13,000 performances.

4) In Norse mythology, the Valkyries are divine maidens who serve Odin, the chief god. They are responsible for selecting warriors worthy of entering Valhalla and escorting them to the afterlife. They are often depicted as powerful and beautiful figures, riding winged horses and wielding spears.