This is perhaps on the bucket list of every traveller. Built in the 7th century BC, this wall stretches over 6,000 kilometres and covers multiple cities, landscapes, and climates. It was built to connect watchtowers in ancient times. At present, some parts of the world have been restored and can be accessed safely, while others are ruins. You can either take the long hike across the wall or visit each part of it on different days. Either way, you are bound to be amazed by the wonder of these great constructions.