This might depend on what exactly you said and how exactly your teacher responded, rather than any interpretation or re-phrasing…
Let’s remember first that “I am writing a description of a place and I need to change the sentence” makes sense semantically but is not correct in grammar, and the same is true of “Have you ever wanted to visit a city which is surrounded by green hills and with a beautiful big lake?”
What exactly did you say and how exactly did your teacher respond, please?
“Let me tell you about… (anything)“ is a standard story-telling form going back as far as the history of language, as should be known by every teacher of language beyond the basic.
This can most obviously be seen in the oldest known work outside Biblical scripture, The Epic of Gilgamesh, which in various translations does specifically include the phrase “let me tell you about…”.
That being the case, who could ever suggest, let alone prove, that any grammatically correct use of the same semantic form was in any way “wrong”?