Metro Plac Wilsona (Wilson Square after Thomas Woodrow Wilson, the 28th president of the USA) is a busy station of the only metro line in Warsaw, open since 2005. It's modern, clean, with efficient entry system and even won an architecture award.
Metro Plac Wilsona won the MetroRail 2008 award of being then the best recently constructed station in the world. It looks like a giant shell or the inside of an UFO, but certainly worth checking if you are into modern architecture.
If you keep watching, you can see how the shell-like ceiling changes colour from time to time.