Places
St Mungo's Hospital
St Mungo’s Hospital for Magical Maladies and Injuries treats magical injury and illness behind a department-store front in London. Arthur Weasley is a patient after Nagini bites him. On the closed ward Harry meets Neville Longbottom visiting his parents, who were tortured into lasting confusion with the Cruciatus Curse.

In the books
Harry Potter and the Order of the PhoenixChapter: St Mungo's Hospital for Magical Maladies and Injuries
Harry visits Arthur on the ward named for creature-induced injuries. The hospital is already the place they are told Arthur has been taken.