After leaving Hamburg, the Clemens party traveled by rail to Heidelberg, stopping briefly in Hanover, Wilhelmshohe, Cassel, and Frankfort on the Main. The prettiest effect is a cloud-ceiling in fresco in our parlor at Frankfort. German cleanliness reaches an altitude to which we may not aspire. These peasants are as cleanly in their houses as the Yankee of romance & more cleanly than the reality. Even in the narrow crooked lanes of the old parts of the cities, where the poor dwell, the children are neat & clean -- muchwhite stockings on the little girls. 7 grey cats in one small house in Frankfort-on-the-Main. Each city has its peculiarity -- Frankfort's is its ancient town pumps. The Geutenburg &tc trinity stand opposite our windows. [The Guterberg Trinity, a grouping of statues representing Gutenberg, Fust, and Schöffer, associates in the invention of printing, stood in Frankfort's Rossmarkt.] Legend that Charlemagne arrived at the Main with his army chasing the Saxons, or chased by them -- early in the morning -- fog, & could not see well, -- saw a deer taking her young along, judged shw would seek a ford -- so she did -- C crossed there & resolved to build a city -- which he named the ford of the Franks -- Frankfort -- there's an old bridge there with C's statue on it. In Frankfort, hotel chandelier with 9 burners, but you had to light 8 of them in order to see the other one. Bad gas has no nationality. Boxes established in beer saloons for nubs of cigars for orphans -- the result in money is enormous. The people have such good faces. The uniforms are all bran new. Street car conductor wears bright new uniform, & is as polite as -- as -- but there is nobody at home to compare this politeness with. -- & politeness costs so little. Our national impoliteness is not natural, but acquired. It would be a curious study, how <& whence> & from whom & why we acquired it. Men in garb of gentlemen stare at ladies here in Frankfort just as they do in London. Everywhere the evidences of great freedom & superb government. The "Anlage" full of song-birds. The very schoolboys wear uniform cap. The lower-class women, however nicely dressed, wear nothing on the head in this hot sunshine. The schoolboys carry books in knapsack, apparently. Frankfort is flourishing, & fast being rebuilt & extended.

Railway:

The Main–Weser Railway (German: Main-Weser-Bahn) is a railway line in central Germany that runs from Frankfurt am Main via Gießen to Kassel. it is named after the railway company that built the line and also operated it until 1880. It was opened between 1849 and 1852 and was one of the first railways in Germany.

https://en.wikipedia.org/wiki/Main–Weser_Railway

From Cassel to Frankfort:   Northern Germany 1873  Route 59 page 278