- Well, what's this? Where are we?
- It's the main sewer. Runs right into the blue Danube. Smells sweet, doesn't it?

11 seconds sound clip from the The Third Man (1949) movie soundboard.

You can hear this line at 01:08:29.116 in the Blu-ray version of the movie.

Quote context

[...]

- What about the doorways?

- I tell you, I heard him running ahead of me!

- Yes, yes, yes.

- And then he vanished out there, I suppose, with a puff of smoke and like a clap of...

- It wasn't the German gin.

(Sewer water flowing)

- Well, what's this? Where are we?

- It's the main sewer. Runs right into the blue Danube. Smells sweet, doesn't it?

- We should have dug deeper than a grave.

- You knew him, Major?

- Hmm. Yes.

- Yes. Joseph Harbin. Medical orderly at the general hospital. He used to work for Harry Lime.

- Joseph Harbin?

- Yes. He's the man I told you was missing.

[...]