Pick one category for the following text. The options are - company, educational institution, artist, athlete, office holder, mean of transportation, building, natural place, village, animal, plant, album, film or written work. HM Prison Wandsworth -  HM Prison Wandsworth is a Category B men's prison at Wandsworth in the London Borough of Wandsworth south west London England. It is operated by Her Majesty's Prison Service and is the largest prison in London.
Building