MI5 Headquarters

Thames House, a Grade II listed building located at 12 Millbank in Westminster, London, has served as the official headquarters of the Security Service (MI5) since 1994. Originally constructed in the late 1920s by Imperial Chemical Industries (ICI) in a striking Neoclassical uniform style, the fortress-like structure sits prominently on the north bank of the River Thames near Lambeth Bridge. To accommodate the UK's domestic counter-intelligence agency, the building underwent an extensive £265 million modernization in the early 1990s, which stripped the interior back to its steel frame to install state-of-the-art security systems, blast-resistant features, and advanced communications infrastructure. Due to the highly sensitive nature of the operations conducted inside, Thames House remains tightly secured and is strictly closed to the general public.