MORE ON JULY 7 ATTACK
FINANCIAL MARKETS REACT
View images from London after four small explosions hit the city's transportation network on July 21.
July 7 attacks
Near simultaneous explosions rock the London subway and tear open a double-decker bus during the morning rush hour.
July 7 snapshot
A timeline of the unfolding story from central London.
Coverage of London attacks
NBC News special series
Is airport security better now since Sept. 11? How can you avoid airport aggravation during your travels? An NBC News special series looks at what you need to know.