Sorry guys. Deleted my earlier post whilst trying to add this message.
Apologies for a lack of knowledge regarding MTOW and Max payload flights with the AN-225. Can't imagine it's flown with close to 250,000kgs on too many occasions though??? I was told by a handling agent who has overseen this aircraft on many occasions that it was nearly always carrying bulky items, but was rarely over 200 tonnes.
I have indeed been inside the aircraft, as well as others in the Antonov fleet and it is cavernous. I seem to remember thinking the hold was about as high and wide as an AN-124, but just a bit longer.