The Golden Spike Railroad Tower in North Platte, Nebraska

The railroad switching yard in North Platte, Nebraska is the largest switching yard in the world.
It is a Union Pacific and is run kind of like an airline hub.  Most freight traffic heading east or west across the country runs through North Platte.  When trains get here, they are broken apart and the cars are grouped according to their final destination.  New train consists are made up of these groups and the newly assembled trains are then sent on their way.

In addition, Union Pacific has the largest locomotive shop in the world.  Totally within the main building, about ten tracks are used to hold locomotives under repair.  Each of these tracks is capable of holding about five locomotives end to end.
Around the yard are literally hundreds of locomotives waiting for refueling, minor or major maintenance, or to be assigned to outgoing trains.

The tower has three levels for visitors.  On the ground floor, there is the admission purchase window, the gift shop, an endless loop video, and much memorabilia.  The seventh floor is an open-air observation deck.  Today was very gusty-windy.  We started out there and I took some photos of everything.  The eighth floor is a closed observation deck with protection from the wind.  The photos from here are shot through some rather dirty windows.

There was a retired railroad gentleman on the eighth floor who pointed out stuff going on in the yard and answered questions.
He worked for the railroad from his discharge from the Army during WW=II until his retirement some 20 years ago.
He is unpaid and does the docent thing, in full uniform, as a pleasurable hobby.