Sweden's Vasa Museum is embarking on a colossal four-year project to preserve its centrepiece, a nearly 400-year-old warship that sank just 15 minutes into its maiden voyage in 1628. The Vasa remained at the bottom of the sea until it was salvaged in 1961, becoming one of Stockholm's main tourist attractions. "We know the ship is damaged" explains Peter Rydebjork, the Support Vasa project manager, who adds "we want Vasa to be preserved for the future." IMAGES AND SOUNDBITES ARRANGED IN SEQUENCES