Great Barrier Reef
As with most of the attractions on this list, the main issue here is the potential crowds that you might come across during peak season. As such, it's your choice: get lucky or choose something else. In this case, the gorgeous Ningaloo Reef offers a fine alternative.
Take a dive and you'll greet remarkable marine life including docile whale sharks, humpback whales or rare species of turtle, depending on when you go. A majestic boat tour will unveil the mass coral spawning in March and April, making for an unforgettable experience. The Ningaloo Reef sits on the west coast of Australia and is thus on the opposite side of the country to it's more popular alternative, meaning you're highly likely to avoid the crowds.
See an alternative reef in Australia
Empire State Building
The most famous skyscraper in the world unsurprisingly draws in huge numbers of people to come and see it every single day, which is fine if you're happy to go at non-peak times or simply see it from the ground up. If you do wish to brave the crowds and take the lift to the top, you will probably be met by a rather sizeable queue as you wait for the best views.
Chicago is the home of the skyscraper and boasts an enviable city skyline that you'll not want to miss. In fact, you may grab yourself an even better view with a visit to 360 Chicago's attraction: TILT. Housed on the 94th floor of the John Hancock Tower, visitors lean out from over 1000ft in the air for unparalleled views of the gorgeous city. Just make sure that you have a head for heights!
Head to the heights of the Windy City
Colosseum
The Colosseum of Rome is undoubtedly a stunning sight to see that's full of history and wonder. The amphitheatre today though, is marred somewhat by the scaffolding currently up whilst the historic landmark is renovated.
During that time, it may well be worth considering your options if you choose to visit Rome. A strong option would be the Pantheon, a building also steeped in Roman history and an equally impressive sight. One of the best-preserved Ancient Roman buildings, it has been in continuous use throughout it's extensive history as a church. Explore the site which has been renovated many times, most recently by Hadrian, and bask in it's glory.
Find the glory of the Roman Empire here
A Final Tip
When heading to the Great Wall of China, head to Jinshanling where you'll find a more remote stretch of the wall, offering equally stunning views with a fraction of the crowd.
