Power & Control

Building a layout means you need to expand beyond the original train set controller. There's a whole range of ways to run trains - traditional DC control - DCC and even some automated systems.
Gadgets are our term for useful and novel bits of electronics whilst sound systems add a new dimension to the layout.
Of course by closing the curtains you can bring on night - so make sure you have plenty of street and house lights, plus lights for your railway passengers.
Lastly wires - switches - connectors are all required to send power and signals to the trains.