The largest collection of antique shipwrecks ever found in Norway has been discovered under mud at the building site for a new highway tunnel in Oslo, the project's lead archaeologist said Friday.The archaeologist, Jostein Gundersen, said at least nine wooden boats, the largest of them 17 meters, or 56 feet, long, were found well preserved nearly 400 years after they sank at Bjoervika, an Oslo inlet near the new national opera house.