Breakdown of ¡Ojalá esta mansión estuviera en el paraíso!
en
in / on / by (means of transport) / about (after pensar)
estar
to be (location/state)
este
this (m.sg., also esta, estos, estas, esto)
ojalá
hopefully / I hope (that)
Questions & Answers about ¡Ojalá esta mansión estuviera en el paraíso!
Why do we use the imperfect subjunctive (estuviera) here instead of the present subjunctive (esté)?
We use the imperfect subjunctive after Ojalá to express a wish that is highly unlikely or impossible in the present or future. The speaker knows the mansion is not actually in paradise, so they are saying 'If only it were!'. If they used the present subjunctive (Ojalá esté...), it would mean they are hoping for a real, possible outcome.
Why do we use the verb estar here instead of ser? Isn't a mansion's location permanent?
Could I say estuviese instead of estuviera?
Yes, absolutely. The imperfect subjunctive has two sets of endings: -ra and -se. Ojalá esta mansión estuviese... means exactly the same thing and is completely correct, though the -ra ending tends to be a bit more common in everyday speech.