“Holly Martins: ‘Well, what’s this? Where are we?’ Sgt. Paine: ‘It’s the main sewer. Runs right into the blue Danube. Smells sweet, doesn’t it?’”*

*from “The Third Man, a 1949 film noir directed by Carol Reed, written by Graham Greene, and starring Joseph Cotten, Alida Valli, Orson Welles and Trevor Howard, set in post-war Vienna.” (Wikipedia)

From A Nervous Splendor: Vienna 1888-89 (1979), by Frederic Morton:

https://en.wikipedia.org/wiki/Rudolf,_Crown_Prince_of_Austria

“Rudolf waited to be the next Austrian. And Austria, that many-colored idea sprawling across the Danube lands, surrounded him as he waited, as he sped along the boulevard. Every fairytale corner of the Monarchy contributed visitors to the Ringstrasse. Visiting Vienna meant, above all, walking that boulevard, for seeing sights, for just being there. Exotic apparitions mingled among strollers in Western attire. As Bratfisch swooshed past, a Muslim — from the Imperial Protectorate of Bosnia – shuffled along in crimson fez and pointy white slippers, hawking ornate teakettles and inlaid snuffboxes. Coptic priests, with mitres and beards and violet waistbands girding dark-green cassocks, trooped beside Hasidim in black silk caftans and large-brimmed beaver hats. A Carpathian peasant took off his white fur cap before crossing the wonderful street — a form of Balkan humbleness. And few of these strangers in Vienna would ever guess who sat in the headlong carriage…

…a woman walked singing to the window of a villa in Döbling, at the lovely edge of the Vienna Woods. Singing, she jumped from the third floor. She kept singing the Imperial anthem right up to the thud. A rosebush broke her fall, and the ambulance brought her to the psychiatric retreat of Professor Leidesdorf close by.

She was not the only one. Another woman in the news at this time (whose name was also withheld by the papers) entered a church in the elegant Hietzing district…She, too, ended the day at the Leidesdorf retreat.
So did a Herr M., a director of the Danube Steamship Company.
Suddenly, while playing billiards, he accused his opponent of being an anarchist plotting to gun down the King of Greece. He tried to stab “the assassin” with his cue stick. Police officers took him into custody until attendants from the Leidesdorf retreat took over…

…the Donaudampfschifffahrtsgesellschaftsball, an evening with the longest name and the most panoramic decor. For this Danube Steamship Company’s Ball the entire premises of Harmony Hall turned into a giant steamship, complete with the swash of real water, the sounding of real foghorns, with sailors, sea nymphs, and a waltz band revolving vertically on a titanic paddle wheel. At the height of the nocturnal “voyage” the real Chief Admiral of the Austro-Hungarian Navy appeared on the “bridge” and watched gentlemen launch a number of ladies in “lifeboats” into the “sea.” But nobody really disembarked before 6 A.M.”

“The famous death scene, in which Harry Lime’s fingers grasp through a sewer grate, had to be filmed in a London film studio because Vienna’s sewer grates were too thick and the openings too narrow.
Many scenes show Vienna although they were filmed at the studio in London.
Little Hansel got his role by chance when he visited his father, a lighting technician, on set.” (Stadt Wien)