The Miniatur Wunderland in Hamburg, Germany has more than: 700 trains, 4,000 automobiles, 165,000 trees and 250,000 individual lights and a track lengh of 5.6 miles has set the world record for the largest miniature railroad. Details here:
http://www.worldrecordsacademy.org/biggest/largest_miniature_railroad_world_record_set_by_Miniatur_Wunderland_70942.htm
It will be "ready" around 2014 :)