Okay, here's a real strange one; It's a "what-if" suggestion to a norwegian member of the "Marklin Bar & Grill", who may have to use a closet-like room of only 180cm x 180cm(!) for his layout. No windows, and the door opens outwards.

 

I've opted for a sandwich-layout with two scenic levels, and a lower level with a shaddow-station. Connecting all three levels is a R2 helix, with an impressive 7 full rounds! If the shaddow-station is 0cm, the first scenic level is at 20cm and the upper scenic level at 70cm. Note the quite soft curves, although R1 IS used in visible areas, at least it is transitioned to look less harsh.

 

The upper station-level shows a BR03 with 5 long passanger-waggons doing an "umlauf" at the station. -Just to show what is actually possible in this small space. But I admit it might be more sensible to concetrate on smaller rolling stock, and use the Roco turn-table instead of the bigger Marklin TT. With the integrated return-loop on the middle level, trains can do rounds without having to go up to the main station and be turned around.