I had read about Northlandz in Model Railroading (Sept. '95, I believe), and had to drive through New Jersey over the weekend, so I stopped by. In short, it's amazing!
Northlandz is the largest model railroad in the world, as far as I know. It's 52,000 square feet, but up to 30 feet high, so effectively the modeling is more like a 150,000 square foot single-level model might be. There's a 6-foot-wide passageway from which you can view the railroad at multiple heights. The viewing passageway is ONE MILE long! The railroad itself has over eight miles of HO track.
The interesting thing is that the modeling varies from extremely well-done to somewhat crude, but the overall effect is still impressive. What they show is that if one is building a model railroad (rather than a railroad of models), the effect of getting a scene done and directing attention to some nice elements within it is not dependent on everything being of prize-winning quality. The 300-400 bridges on this layout vary from small and humble to the mightiest I've ever seen. An HO train traveling over a 20-foot-long bridge over a 15-foot-deep gorge is an attention-getter!
I have no connection to Northlandz, but if you're anywhere near Flemington NJ (an hour from NYC or Philadelphia), it's worth $13.75 admission to see this railroad. They're open 7 days a week, and the website is
www.northlandz.com.