The decision was announced yesterday in the redundant 500-ft turbine hall at Bankside by Nicholas Serota, the director of the gallery. However, the decision came as no surprise - Mr Herzog and Mr de Meuron were known to be the favourite choice of the competition judges before Christmas.
Mr Herzog and Mr de Meuron pipped five rival firms of architects to the post, including David Chipperfield, the only British architect on the Tate's competition shortlist.
The conversion of Bankside is expected to cost about £80m and the Tate hopes half of the cost will be met by a contribution from the Millennium Fund raised through the National Lottery. Work is expected to start next year, with the gallery opening in 2000.
The scheme will bring relatively little change to the stark exterior of the Fifties power station, and the vast turbine hall will be retained as far as possible as it is, serving as a vast lobby. The gallery, which is expected to act as the major elementin the revival of a run-down area of Southwark, is expected to attract up to two million visitors a year.
Swiss Bankside, page 25