The Clerkenwell House Of Detention, a dark, damp and disused prison site, was originally built in 1845 and soon to became London's biggest remand prison with up to 10,000 prisoners a year. Records of incarceration on the site however go back as far as the 17th where many thousands were subject to terror and torment. Most of it was demolished in 1890 but the wardens residence and the entire underground level of the prison was left intact. Some underground cells became air raid shelters during the Second World War, and more recently In 1983 the doors were opened to tourists.