"We don't know where the library is."

Translation: No sabemos dónde está la biblioteca.

[Chloraflora]

Why does conocemos not work for this sentence?

[Jim8161]

Knowing the location of an object (even a building) is knowing a fact or information, so «saber» is the appropriate verb.

Ref : https://studyspanish.com/grammar/lessons/sabcon

[WestAlO]

no sabemos donde la biblioteca esta? why is this wrong?!

[TykaBooker]

The word order is wrong. Read #3... https://grammar.collinsdictionary.com/us/spanish-easy-learning/asking-questions-in-spanish

[NeoMoonGoddess]

Why is "lo" not needed? I thought it was: "No lo sabemos dónde está la bibliotecca?" - ¡Gracias!

[Jim8161]

"lo" is a direct object pronoun that means "him", "you", or "it". None of those words are in the sentence to be translated.

A direct object pronoun would be used to replace a noun, but the noun ("la biblioteca") is included here.

[hasimmons]

Why does dónde require the accent here, when the sentence is a statement not a question?

[Jim8161]

The sentence contains an indirect question
Here is an article with explanation: https://www.thoughtco.com/orthographic-accents-in-statements-3080304