The Stachus underground structure situated at Karlsplatz, also known as Stachus, between the main station and the city centre is one of the most important public transportation hubs in Munich. Apart from providing access to the U-Bahn station, S-Bahn station and trams, the space is an extremely busy shopping mall and food court.The intention of the redevelopment of the intermediate level between the road and the tracks with barriers and ticket booths, which was built in the 70s mainly for this purpose, was to transform the area into being part of the greater urban space. On a horizontal level, it connects the urban areas Marienplatz and Hauptbahnhof. The shape of the circular Stachus plaza has been adopted as a major feature in the design of the underground level. The vertical link created here between top and bottom enables visitors to more easily find their way around the subterranean roundabout. As a result, the heterogeneous building stock has been reduced and is now perceived as part of an overall concept. The geometric shape of the circle is also the characteristic feature of the ceilings. A multi-functional light installation links the diverse zones by using different size circle segments. In connection with the light terrazzo floor, the reflective ceiling generates a quality of light almost resembling natural daylight. Bronze-coloured metal facades with large shop windows emphasise the urban character of this busy thoroughfare. In the same way as the urban space flows into and is continued beneath the ground, the subterranean space penetrates the surface and is raised above ground in the form of signaletics and the design of the entrance and exit zones. Whereas the artificial light mimics the character of the supersurface below ground during the day, the subsurface atmosphere protrudes above ground through illuminated zones and eye-catching light stelae at night.