"We don't know where the library is."
Translation:No sabemos dónde está la biblioteca.
Duolingo has admonished many times that, "generally," for permanent situations, one uses "es" and not "esta." I was called out for using "es" previously in this lesson, made the change and it's now ruled correct. If a library is not the epitome of permanent versus temporary, I don't know what is. Explain yourself, Duolingo.