Now that's a big vise. You probably don't have to clamp things in it to hold them, because it has enough mass to have its' own gravitational field.
That is even bigger than the vise an old friend of mine "borrowed" from a ship when he was working in a shipyard, when I was in college. He asked me to come over and help him move something into his Dad's basement. He popped the trunk lid of his old Pontiac Ventura, and this huge vise pretty much filled the trunk. We used an engine cherry-picker to get it out, and about killed ourselves getting it into the basement workshop. I asked him how in hell he managed to get it off the ship. He simply said, "Don't ask. The old man wanted a bigger vise, so this is what I got for him."
I've been in a lot of steel mills, large factories, machine shops, fab shops, etc., and it was by far the largest vise I've seen. I wasn't into vises back then, so no recollection who made it.
