Located near Salisbury, England, this megalithic structure is over 3,000 years old, and its stones come all the way from Wales. Scholars still are not sure how the builders got the stones there and have tried to replicate the feat, with dismal results. Moreover, we only have a vague idea to its purpose (we’re basically just guessing). Stonehenge is now fenced off, and you can no longer go into the circle; visitors can only walk around the attraction. But it’s worth visiting for the mystery behind it and an excellent and detailed audio tour.