[custom_adv] MS Harmony of the Seas is an Oasis-class cruise ship constructed by STX France at the Chantiers de l'Atlantique shipyard in Saint-Nazaire, France or Royal Caribbean International. [custom_adv] With a gross tonnage of 227,700 GT, she is the largest passenger ship in the world, surpassing her older sisters MS Oasis of the Seas and MS Allure of the Seas by some 2,000 gross tons, as well as 2.15 metres (7.1 ft) in length. [custom_adv] The success of the first two Oasis-class ships led Royal Caribbean Cruises to order a third ship of the type in December 2012. Harmony of the Seas was floated out on 19 June 2015, began her first sea trials on 10 March 2016, and was delivered to Royal Caribbean on 12 May 2016. [custom_adv] After a build time of 32 months, the ship first set sail on 15 May 2016 from the STX France docks in Saint-Nazaire, viewed by some 70,000 people. Her initial destination was Southampton, England, although the home port will be Barcelona, Spain. [custom_adv] For the inaugural season to commence 7 June 2016, Harmony of the Seas will offer seven-night western Mediterranean cruises originating from Barcelona and Rome (Civitavecchia). [custom_adv] At the end of the summer and autumn season (in late October 2016), the ship will cross the Atlantic to the United States, where she will offer seven-night eastern and western Caribbean cruises originating from Port Everglades, Florida and Port Canaveral starting in November. [custom_adv] Harmony of the Seas has 2,747 staterooms, with a wide variety of types, to accommodate (at double occupancy) 5,479 guests ranging from small interior rooms through larger rooms to suites, some of which are fitted with wall-mounted 80-inch screens, covering nearly the floor to ceiling, that show the ship's environment as if through a window, named 'virtual balconies'. [custom_adv] These screens were first fitted on the Quantum class of cruise ships. A full 43 categories of stateroom types are offered, starting at a size of 180 square feet; several types of suites are available, including the new Royal Class. [custom_adv] The £783m vessel, which came into Southampton earlier, is 361m (1,187ft) long and can carry 6,780 passengers.It features 20 restaurants, 23 swimming pools and took more than two-and-a-half years to construct. [custom_adv] The 70m (230ft) high cruise ship had its first trial in March when it was guided out to sea from the port of Saint-Nazaire.It will leave Southampton for a four-night cruise to Rotterdam on 22 May.On 26 May it will leave the city again for a three-night cruise to Cherbourg before finally leaving Southampton for its summer base of Barcelona on 29 May.