Many years ago I started reading a novel (that was missing the ending) about a Greek veteran of the Persian invasions with a head wound who couldn’t recall events of the previous day, so took to writing them down on a scroll he had to re-read each morning. There was a reference to him and his companions being taken prisoner/ as slaves to the “City of Rope” in the central Peloponnesus, that the accompanying map inferred was the city of Sparta. Was there an actual city called Sparta, and/or an ancient Greek city with the name of “ROPE”?
The book you read is called "soldier of the Mist" by Gene Wolfe. Its central conceit involves a Latin speaking soldier travelling through the Greek world but not really understanding what he sees or hears. (As you mentioned, he has no short term memory)
Often, he will interpret the things he hears in an over-literal fashion. Therefore, in the story, he renders Athens (named for the goddess of wisdom) as "Thought".
"Rope" is based on a similar misunderstanding. He is actually referring to Sparta itself. (Which obviously was an actual city, about which much can be found on this sub if you're interested.)
The author explains this in the book's author's note. He claims the protagonist is mishearing the word for "cord," "Sparton"
Edit: for those reading the book, this is a helpful list of "translations".
So, the definitive thing to look at is the Index of Classical Poleis, which I don't have. I checked my available handbooks and dictionaries and couldn't find one, and I couldn't find one at the Ancient Mediterranean Mapping project.
I wonder, though, if that isn't a description, and not a noun, like you might refer to Los Angeles as the City of Stars? Is there context to support a use like that?