This, they say, is the biggest model railway in the world, scale 1:87 (H0), placed in a hall of 3000 m2 in size:
http://www.loxx-berlin.com/en/index.html (English). Check "Pictures and Videos" and switch between both categories.
German (slightly bigger website):
http://www.loxx-berlin.com/de/index.html
The model railway is located in Berlin, has just moved to a new, greater location at Alexanderplatz, and gives an image of a miniaturized Berlin in scale 1:87. In order for a new A380 model to be presented (animated during taxing and take-off !! ), the whole airport section had to be reconstructed, due to the weight of the new model.
It has been on German TV repeatedly, and I once saw it years ago, in real life. It is a giant monster. The control centre now has over 50 computer terminals. Total length of all cables build into the model installation is over 70 km, all cables needed to control it all are 700 km. They construct all models and buildings themselves, and all trains needed manual reworking and constant maintenance due to the constant use, they also built vacuum-cleaner trains and camera trains. 400 trains simultaneously running. 5 km of railway tracks. 55.000 figurines, 1200 buildlings, and countless moving cars and trucks and airplanes. Manual workers for example spend up to 3 weeks to equip a single model truck with up to 300 mini-LEDs. For full operation, a staff of 40 people is needed.
For the recent moving to a new location, 240 huge truckloads were needed.