16. Здание будут строить.

The Russian phrase "Здание будут строить" translates to "The building will be built" or "They will build a building." This indicates a future action. Let's analyze the German options:

1. "Man baut ein Gebäude." translates to "One builds a building." This is present tense and does not match the future tense of the original phrase.
2. "Man wird ein Gebäude bauen" translates to "One will build a building." This correctly uses the future tense (werden + infinitive) and is a direct translation of the intended meaning.
3. "Das Gebäude wird gebaut." translates to "The building is being built." This is in the present passive voice and does not convey the future action.

Therefore, the most accurate translation is "Man wird ein Gebäude bauen."