2,500 workers have spent 10 million work hours to complete the vessel since September 2013

The world's biggest-ever cruise ship, the 120,000-ton Harmony of the Seas, a luxury home on the waves for 8,500 passengers and crew, was handed over by a French shipyard on Thursday after a 40-month engineering feat.

At 66 meters, it is the widest cruise ship ever built, while its 362-meter length makes it 50 meters longer than the height of the Eiffel Tower.