The Construction of Supertankers (36 pics)
Let me quote Wikipedia:
The Batillus-class supertanker is a class of the biggest ships by gross tonnage ever constructed. At 555,000 metric tons deadweight (DWT), and 414-metres, the four vessels were built in the Louis Joubert Lock, and launched from the shipyards of Chantiers de l'Atlantique at Saint Nazaire, France at the end of the 1970s.
The only other ship considered larger was the Seawise Giant (ex-Jahre Viking, Happy Giant and Knock Nevis) of 1981, which was originally designed with a smaller tonnage than the Batillus class, but had her length and tonnage increased during construction.