The buildings are held to a metal plate on the base with magnets. This area is a lift out for track access.
A/D Track Halland Yard / North Union Station
Two 3/8" x 3/8" x 1/8" Rare Earth (Neodymium) magnets side by side to make a magnetic uncoupler.
Magnetic Uncoupler - MTL Permanent Magnet uncoupler installed between the tracks in Halland Yard.