In the lower level of the Casa Del Balboa building in Balboa Park is one of the world's largest indoor model railway displays. There are several rooms, where you can see huge displays of trains going through miniature towns and landscapes. Parts of the California railway system is recreated in miniature, including the Southern Pacific-Santa Fe Tehachapi Pass (pictured here).
There are different miniature towns representing San Diego and other California cities throughout various point in history, and the railways that went through them at that time period.
In another room is the toy train gallery, with four separate lines, miniature scenery, and even a train equipped with a camera in the front, so you can watch a video from the 'train's eye view.'
Both kids and adults will enjoy this fantastic model railroad museum.