Queen Mary 2 (QM2) was built at Chantiers de l'Atlantique St. Nazaire (now part of STX Europe) for Cunard to relieve Queen Elizabeth 2 from frequently undertaking Atlantic crossings. When finished in 2004 QM2 was the largest passenger ship ever built. Sadly her inauguration was overshadowed by a fatal accident where fifteen people were killed during a visit of the nearly finished ship. (see this BBC article)
QM2 is presently the only passenger ship undertaking Atlantic crossings on a more frequent basis. Although built as a fast ship for frequent Atlantic crossings Queen Mary 2 offer accommodation and amenities comparable to other contemporary passenger ships.
For a brief technical description of QM2 visit ship-technology.com. A lecture by Dr. Stephen M. Payne on the design and construction of Queen Mary 2 is available at YouTube.