Imperial College is one of the colleges of the University Of London, with a strong science and engineering reputation. In the early nineties the college merged with a nearby training hospital and became the "Imperial College of Science, Technology, and Medicine", though who knows what it is called now.
The campus of Imperial is centred around South Kensington, but also includes outlying departments and buildings from the spate of mergers in the University of London. The main Imperial buidings are surrounded by the Royal Albert Hall to the North, the Science Museum to the South, and the Victoria and Albert Museum to the south east.
For more information, see the IC website and mt99's writeup on Everything2.
Imperial College has numerous lively social clubs, including a science fiction society ICSF who hold a one day science fiction convention each year. http://www.su.ic.ac.uk/icsf/social/events/picocon_20.html