Ok, let me be honest: I did not build it! I bought it! I will make a few little scenic changes in the years to come.
I am however installing it and I wonder if that is/was not more difficult...
Its a classic dog-bone layout, double tracked with a reverse loop. The mountain is removable for maintenance and trouble shooting but the biggest surprise of it all - its Kato Unitrack all the way!!! Length is 4.1m by 0.8m at the widest. Layout wired for DCC with a Digitrax auto reverser in (AR) and all wired Kato switches and a double crossover. Lovely stuff these...
It was build by Graham Page (a builder of anything railways extraordinaire) who decided he needed to fixate on his live steam building exercise rather. I have seen what's he done so far - amazing does not describe it remotely... wonderful craftsman!
Any way, enough bragging with someone else's work. Some pics to brag even more

The last 2 pics show my shelves up on the wall, complete with tons of crap! That took hours to remove. Then they were removed off the wall and modified... Hellava job!!