Interrogative pronoun: Where?
Relative pronoun: I know where you have been.
Ubi + indicative:
When: I felt in love when I saw you.
Source: They don't give the meaning with "when" in the Wiktionary (so I guess it's the use is rarer?), but they give it here (in French): http://www.dicolatin.com/FR/LAK/0/UBI/index.htm