I like Bruges, but I love London - there is simply so much to do, whatever your interests. History wise, there is tons to do, The Tower of London is great, St Paul's Cathedral, Westminster Abbey, Big Ben, Houses of Parliament, Hampton Court, and dozens of other places. Non historical attractions like the London Eye, or a Thames river boat trip, or a wander around Greenwich are also fun. Great food - whatever you fancy you can find it, from a great curry, to fine French dining, to a greasy spoon for egg and chips. Tons of bars and pubs, and lots of nightlife from theatre to clubs, to the weird and wonderful! Fantastic shopping, from markets to high end designer, and it is such a walkable city (with the odd hop on the tube for longer distances) you can really see a lot of it over two days.