Quote - if you want scale pre starwars.. there is one that takes all..

the Ringworld

(oneday they may make the movie.....)

Rumour has it that there's a TV movie of Ringworld in pre-production, by the same people who made 'Dune' (is that the Sci-Fi Channel?).

Until then... if by 'cinematic' you mean movies only, then probably the 'Discovery' and the 'Silent Running' ships as already mentioned. If you mean TV as well, two Star Trek vessels come to mind - the 'planet-killer' that someone's noted, and I'm pretty sure there was an asteroid-sized generation starship in one of the episodes as well.