They now turned and took a last look at the Emerald City. All they could see was a mass of towers and steeples behind the green walls, and high up above everything the spires and dome of the Palace of Oz.
Explore these websites and videos to find out more about towers.
13 most famous towers in the world
Scotland has some amazing ancient towers called brochs, built 2000-3000 years ago.
And these are the tallest structures currently under construction.
The Leaning Tower of Pisa is much smaller, but still an amazing building for very different reasons.
Challenge yourself!
One of the most famous towers in the world is the Eiffel Tower in Paris. Your challenge is to explore the view from the top in these amazing virtual tours and tell us what you saw:
You can also look at the Help with Challenges page to come up with your own tower challenge.
