London is the capital city of England and the UK as a whole.  Many events in the Power of Five series took place in London, as shown below.


Matt and his parents -- Mark Freeman and his wife -- lived at a house in Dulwich before the couple's death in a car accident.  Rosemary Green, the Freemans' neighbor and Matt's babysitter, lived at another house in Dulwich.


In Raven's Gate, the members of the Nexus met at a Victorian building in Farringdon.  The building had survived World War II, and there were timed lights inside to give the impression that the building was occupied.


In Raven's Gate, Mrs. Deverill arrived at London to pick up Matt through Holborn Station.  It was at Holborn, in a fairly empty alleyway, that Mrs. Deverill was attacked by Will Scott, the latter whom was later found dead.