What vessel, originally designed for civilian transatlantic service, was converted into a troop transport during World War II and later became a floating hotel and tourist attraction?

1. It was known for its luxurious accommodations and speed prior to its wartime conversion.
2. During its wartime service, it transported thousands of soldiers across the Atlantic.
3. After the war, it was refitted and became a popular stationary attraction.
4. It is no longer afloat, having been scrapped in the late 2000s.