The basic and most obvious way is ¿Dónde está..? If you wanted to sound really posh, you could say “¿Dónde se encuentra…?2 or even (especially in Latin America) ¿Dónde se ubica…?, but you wouldn’t really use either of these expressions in conversation.
Good old Quora has collapsed several perfectly good answers (and a couple of dodgy ones) but has so far failed to collapse one absolutely dire one from someone whose credential says “knows Spanish” but who clearly does not.
