Actually .... This isn't the largest model railway layout in the world.
There's one called Northlandz in New Jersy that is larger.
Northlandz has 8 actual miles of track (but is fully built out).
Wunderland in Germany has 6 actual miles of track (but has a plan in place to expand by another 6 miles).
Here's Nothlandz web site: Northlandz
I'm also into this hobby. I have an extensive HO and HOn3 collection. I used to be a part owner in a hobby (mostly trains) store but had to get out of it as my ex-wife and her attorney
thought they were entitled to half it's value since I was the president of the corporation we set up. That was a really fun place!