Given the question: 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. Harefield Hospital - Harefield Hospital is located in Harefield within the London Borough of Hillingdon. It is part of the Royal Brompton and Harefield NHS Foundation Trust which describes itself as the largest specialist heart and lung centre in the UK and among the largest in Europe. Harefield's sister hospital is the Royal Brompton Hospital in Chelsea. The hospital grounds include tennis courts (no longer in use) and a helipad.
The answer is:
Building