Tate Modern was created in the year 2000 to display the national collection of international modern art (defined as art since 1900).

By about 1990 it was clear that the Tate Collection had hugely outgrown the original Tate Gallery on Millbank. It was decided to create a new gallery in London to display the international modern component of the Tate Collection. For the first time London would have a dedicated museum of modern art. At the same time, the Tate building on Millbank would neatly revert to its original intended function as the national gallery of British art.

An immediate problem was whether the modern art gallery should be a new building or a conversion of an existing building, if a suitable one could be found. As a result of extensive consultations, particularly with artists, it was decided to search for a building to convert. When the building that is now Tate Modern presented itself, it appeared something of a miracle. It was a former power station that had closed in 1982, so it was available. It was a very striking and distinguished building in its own right, by the architect Sir Giles Gilbert Scott. Not least, it was in an amazing location on the south bank of the River Thames opposite St Paul’s Cathedral and the City of London.

A national architectural competition was held attracting entries from practices all over the world. The final choice was Herzog and De Meuron, a relatively small and then little known Swiss firm. A key factor in this choice was that their proposal retained much of the essential character of the building. One of the shortlisted architects had, for example, proposed demolishing the splendid ninety-nine metre high chimney, a central feature of the building.

The power station consisted of a huge turbine hall, thirty-five metres high and 152 metres long, with, parallel to it, the boiler house. The turbine hall became a dramatic entrance area, with ramped access, as well as a display space for very large sculptural projects. The boiler house became the galleries. These are on three levels running the full length of the building. The galleries are disposed in separate but linked blocks, known as suites, on either side of the central escalators. The Tate collection of modern art is displayed on two of the gallery floors, the third is devoted to temporary exhibitions. Above the original roofline of the power station Herzog and De Meuron added a two-storey glass penthouse, known as the lightbeam. The top level of this houses a café-restaurant with stunning views of the river and the City. The chimney was capped by a coloured light feature designed by the artist Michael Craig-Martin, known as the Swiss Light.

 At night, the penthouse lightbeam and the Swiss Light mark the presence of Tate Modern for many miles.