If you want to get a bird's eye view of London, there are several ways to "rise above" and take in the spectacular views of the landmarks, the skyscrapers and the river (not to mention the over 7 million people scurrying around). You'll want to bring your best camera equipment to capture your memories.
First and most obviously, the London Eye is the newest and still one of the most popular tourist destinations in the entire city. Over 400 feet tall, this observation wheel (not to be confused with a ferris wheel, where people are suspended from open seats or cars) contains 32 air conditioned and fully-enclosed capsules. Rotating at less than a mile an hour, a full rotation or "flight" takes thirty minutes. The wheel moves slowly enough that it continues to move as passengers step onto and out of their capsules, but it will stop for elderly and disabled passengers. From the top, on a very clear day, you can see as far off as Windsor Castle - 25 miles away.
A basic ticket is £13 for adults and £6.50 for children. Booking via the Internet saves you 10%. If you have money to spend, skip the usually-long queues and take the "Fast Track" -- £25 to cut right to the front of the line -- or book a champagne flight or private capsule! There isn't a more luxurious way to see the city.
If you're looking for a less modern (and less expensive) way to see Big Ben and St. Paul's from on high, perhaps a visit to Christopher Wren's 1671 column, the Monument, is the way to go. At 202 feet tall, it's the tallest freestanding column not only in England, but in the world. While the London Eye is air conditioned, the Monument's viewing gallery is cooled by Mother Nature. Enclosed by bars instead of glass, you're able to hear the sounds of London below. With admission running £2.00 for adults and £1.50 for children, there has to be a catch - and there is. Visitors need to climb a 311-step spiral staircase to get to the top. Once you have ascended and descended the Monument, the kind people of the City of London (who operate and maintain this tourist attraction) will give you a Certificate of Achievement.
For just £3.50 more per person, you can visit a third popular viewing area from which to take spectacular photographs of the city. The Tower Bridge Exhibition, along with providing a very interesting multimedia presentation about the building of the bridge in the 1890s, will give you access to the high-level enclosed walkways above the Thames. Unlike the half-hour London Eye experience, here you can take your time and look eastward and westward over the river and take pictures either through the glass or through specially-designed glassless windows. The ability for tourists to use these smaller windows is a definite benefit - no more flash reflections obscuring your views of London.
Finally, eight stories above the Thames you'll find the Oxo Tower Bar, Brasserie and Restaurant. Depending on how much money you want or have to spend, you can enjoy a drink, a casual lunch or a romantic gourmet dinner - all with a gorgeous view of the city as seen from the South Bank. You definitely need to book in advance, but you can do so online from here in the States before beginning your vacation. This is a popular spot with visitors and locals alike, so make reservations early.
Regardless of how to decide to see the city, be sure to make time to visit one of these "high above it all" spots during your stay in London.