Comments: 4
Both are gates in the medieval city walls of German cities -- Auertor in Vohburg on the Danube; Isartor in Munich.

("Tor" = "gate"; Isar = the river in Munich.)
I should have remembered, tor = gate! And I was thinking surely, wasser = water. Does "auer" or "isar" have an independent meaning? My confusion regarding the text is cleared up, now, thanks! The specific painting is a view of Munich from an island in the river, btw.
Isar is the river in Munich -- according to Wiki (https://en.wikipedia.org/wiki/Isar), the name is just a remnant of the ancient Indo-European word for water (either flowing or frozen -- cf. "ice" / in German: "Eis").

"Auer" is an antiquated (pre-18th/19th century) form of "in den Auen" -- "in the meadows". It's part of plenty of location names; e.g., there's a part of Bonn, too, that is called Auerberg ("the hill / mountain in the mdeadows" -- or "of the meadows"). Btw, looking up this bit, I found that there is also an Auer Mühlbach ("mill brook in / of the meadows") in Munich. So, Canaletto's "Auertor" may actually be located in Munich as well.
Ooh - thanks for info! Yes, when the text mentions "Auertor" it is definitely discussing a place in the view of Munich under discussion.