Rococco Mirror

Part of a deceased estate my wife has inherited, this mirror is huge approximately 6ft wide, we have been too scared to take it off the wall as its just too big. Its heading from its home in Hungary to New Zealand soon so another chapter in its life is soon to start. From family pictures it has been on the wall since the 60s at least. Its very dirty but im sure with a gentle clean it will come up like a new one. Any tips for cleaning the frame up. Or advice on where its from appreciated.