Answer
(Fatwa: 806/623=L/1430)
At a place where someone can guide to the qiblah, if salah was performed to any direction other than qiblah without enquiring, the salah must be performed again; since when you shifted at a new place you must have performed the salah after enquiring about the same, and you perform salah without enquiring just relying upon your guessing; therefore the salah should be performed again. But, if you had been at place where none was to guide you and you would have performed the salah to a wrong direction, then it would have not been necessary to re-perform the salah.
(2) It is better to ask the visitors as well to re-perform the salah; since it is wajib upon them as well.
Allah (Subhana Wa Ta’ala) knows Best
Darul Ifta,
Darul Uloom Deoband