How big is a Lego Corellian Corvette at minifig scale? Damn huge. It currently is at 12 feet long, with fully detailed interiors. Its creator also made a minifig scale Millennium Falcon, the world's largest:
Lego Corellian Corvette Tantive IV
Lego Millennium Falcon
Craig Steven—the British Lego artist who did the Tantive IV—says that the bridge section alone measures 75 x 50 centimeters, and its interior includes the sets from A New Hope:
The model features a fully detailed interior, based on the sets built for Star Wars: A New Hope. I have drawn up my own diagram of the the corridor network, which actually matches the "real thing" unlike the official plans available in Star Wars publications. I did not use Star Wars: Revenge of the Sith as a source of reference, as the cockpit set constructed for the film was far too small.