A rabbit warren layout is a model railway layout. A group of designs, more than a single constructed layout, rabbit warrens provide a humorous display of continuously moving trains that appear to pop in and out of tunnels, seemingly randomly. The rabbit warren design has a number of key, defining features: * Continuous running in a loop * Tight radius horseshoe curves * Much of the track is hidden by tunnels, with many openings. * Climbing to more than one level, often by spiral tunnels, permits tracks to cross over each other.