Visit the London Eye:
The London Eye really has to be included in a trip to London. The 32 capsules carry around 10,000 visitors every day. Because of the way the capsules are suspended it allows for a full 360 degree-panorama when you're at the top of the wheel. Tickets can be booked online, which really is the right thing to do as it saves a lot of time. The queues look long when you arrive but they move quickly as everyone is issued with a timed ticket. Don't forget to bring your camera!
Check out the Tate Modern:
The Tate Modern is situated within a converted power station and has an imposing position opposite St. Paul's Cathedral along the River Thames. You can visit again and again as it's free and the modern art displays change quite frequently. You'll often find enormous 'installations' in the Turbine Hall on the ground floor. Right outside is the Millennium Bridge. Don't forget that you can take the Tate Boat between the two Tates and the London Eye as well.
Museum of London:
If you're interested in London's history then this is the place to visit. The museum has seven permanent galleries displaying just some of the amazing wealth of material in their collections. Learn about London from the days when the whole population would fit on one double decker bus! Make sure you see the Lord Mayor's Coach, which was built in 1757 and is still used every year for the Lord Mayor's Show.
Natural History Museum:
The Natural History Museum is all about discovering the natural world around us and appeals to all age groups. One very popular sight is the enormous Blue Whale. This is outrageous to see as you really can't imagine how big a life-size model has to be until you walk underneath it. Also don't forget to checkout 'The Power Within' where you can experience what an earthquake feels like!