— -- The 11 cars that make up ABC's "Whistle-Stop Express" are a technological marvel -- stuffed with satellite dishes, high-end television equipment, servers bringing rolling WiFi access, and plenty of really expensive contraptions that do I know not what.

And car No. 11 -- the caboose -- carries ghosts and whispers that connect the train with political history.

It's the Pennsylvania 120 -- something that meant absolutely nothing to me before this trip, either.

But to train buffs, this is the Hope diamond -- one of the most storied and expensive pieces of Americana.

Built in 1928, the car carried every president from Herbert Hoover to Lyndon Johnson. Rat Packers Frank Sinatra, Dean Martin, and Peter Lawford once chartered it.

Perhaps most famously, the car carried Robert F. Kennedy's body from Los Angeles to Arlington National Cemetery in Virginia in 1968, in a journey that drew millions of mourning Americans along the tracks.

A great article in Cigar Aficionado, from 1998, tells you everything you need to know about the train and its owner, Bennett Levin.

From the outside, the most striking feature is the observation deck -- one can imagine a politician's wave to curious crowds, back in the era of whistle-stop campaigning.

Inside, it feels and smells like the Roaring '20s -- rich walnut, etched glass, red velour couches, walls decorated by paintings of trains. (Walking through, I felt like I would open a door onto the poker room from "The Sting.")

Not a bad way to see the country.