There is one in the Natural History Museum in London.
They can reach up to 80 feet in length (think thats about 25 metres). I suppose that about the length of about three buses and as high as a two storey building.
Roughly measuring 100feet long, which is the length of our garden.
David Attenborough has just said they are three times the size of the largest dinosaur. You'll have to look that up as I'm not up on dinosaurs, but at a guess I would say it was the Brontosaurus.