Earlier this week I came across an interesting German HO tram layout known as Gummersbach Strabenbahn. The original layout was a rectangle, but later videos show two additions on either side of a central control panel. In the videos it runs two rail (which seems to be accepted in Germany judging by Kleine Straßenbahn ganz groß videos but not so much in North America). Later videos show the addition of line poles and some overhead.
There is a central three track square or platz which is the focus of the layout. Trams are continuously coming and going. Trams loop around either end and across the top of the layout. It is a complicated track plan with reversing loops. All this is controlled from a central control panel.
Videos by choppernachladung.
The Tatra trams common in the old Soviet block were scratch built using plastic and Halling drives.
There is mention that the track is Luna, which offers asphalt and paving stone surfaces, but I think his intersections are self built.
The modeller calls this layout Neu Gummersbach and this video during the construction of the new layout gives you an idea of the initial track plan.
I am planning a variation of this layout for running my Japanese trams.I find this layout much more interesting and challenging than just running trams around and around.