RMS Titanic was the second of three Olympic class ocean liners - the first being RMS Olympic and the third being RMS Britannic - and was built by the White Star Line, one of the largest shipping companies at the beginning of the 20th century. It was constructed by the Harland and Wolff shipyard in Belfast, Ireland. The Titanic was the largest and most luxurious liner at that time, and was even referred to as the "unsinkable ship".