The oven is REALLY heavy (1,000 kg), and cannot be disassembled. It is so large that it wouldn't fit though the door which is why we used the crane to put it inside before the roof was finished. Having it inside was an important step, but we still had to move it to the ground floor (about 4 meters down). We discussed several possible solutions, but ultimately decided on a simple chain hoist, and 5 people to push and steady it with ropes.
I know in the world of engineering, 1,000 kilos is not really a lot, but it was enough for me... I wouldn't want it to fall on my head!
We had to attach the chain hoist to a second position to get the oven down to the ground. There were some nervous moments, but ultimately, we got it down without even a scratch.