The first RMS Windsor Castle, along with her sister, RMS Arundel Castle, was an ocean liner laid down by the Union-Castle Line for service from the United Kingdom to South Africa. Originally laid down in 1916, their construction was held up by the First World War. They were not completed until 1922. They were the only four-stacked ocean liners built for a route other than the transatlantic. During the thirties, Windsor and Arundel were given refits to make them look more modern. This included reducing their funnels from four to two, and they both were given raked, more modern bows, which slightly increased their length.