Thames House is an office building in Millbank, London, on the north bank of the River Thames adjacent to Lambeth Bridge. Originally used as offices by Imperial Chemical Industries (ICI), it has served as the headquarters of the United Kingdom's internal Security Service since December 1994. It also served as the London headquarters of the Northern Ireland Office (NIO) until March 2013.

Millbank is an area of central London in the City of Westminster. Millbank is located by the River Thames, east of Pimlico and south of Westminster. Millbank is known as the location of major government offices, Burberry headquarters, the Millbank Tower and prominent art institutions such as Tate Britain and the Chelsea College of Art and Design.