Berlin U Bahn Hausdurchfahrt. Because building underground in berlin is not as easy as pie. All lines except the u4 operate by night on weekends and holidays.
Every station has communication pillars at which passengers can talk to someone at bvg’s or deutsche bahn’s control rooms via a direct line by the push of a single button. The best way to where you’re going? This means, you pay around 10 times more compared to other cities with rocky underground.