The Wellcome Trust puts on some of the most engaging exhibitions in London and holds in its permanent collection a number of fine works. Its roots are in biomedical research, but those roots have, with modification, sprouted so many disciplines and areas of tangential enquiry that it makes perfect sense to have commissioned Iain Sinclair to write about the physical and psychological effects of buildings and places on the health of the people who inhabit them, pass through them, long to get out of them, represent them, think about them.