Learn Italian: Non visitiamo questo museo. - We are not visiting this museum.

In Italian, the ending of the verb tells you who is doing the action. The -iamo ending on visitiamo (from the verb visitare) means "we". You could say Noi non visitiamo, but the pronoun noi is usually dropped unless you want to emphasize it.

Why is there no translation for "are" in "are not visiting"?

Italian doesn't use helper verbs like "are" or "do" for basic present tense actions. The single word visitiamo translates to both "we visit" and "we are visiting". To make it negative, you simply put non directly in front of the verb: non visitiamo.

Why is it questo museo instead of questa museo?

The word for "this" (questo) changes its ending to match the noun it describes. Because museo (museum) is a masculine singular noun, you must use the masculine singular form questo. If you were talking about a feminine noun, like chiesa (church), you would use questa chiesa.

How would I use the question words from this lesson to ask "What are we not visiting?" based on this sentence?

To ask a "what" question, you put the interrogative phrase che cosa (what) at the beginning of the sentence. So, "What are we not visiting?" becomes Che cosa non visitiamo?