What renowned prehistoric construction is located in the English county of Wiltshire?

Wiltshire is home to one of the world's most famous prehistoric monuments: Stonehenge. Construction began over 5,000 years ago, around 3000 BC, and continued in stages for centuries. It's a circle of massive standing stones, and its purpose remains a mystery, though theories range from astronomical observatory to religious site. Offa's Dyke, on the other hand, is an enormous earthwork built in the 8th century by the Anglo-Saxon King Offa of Mercia, designed to mark a border with Wales. Hadrian's Wall, built by the Romans in the 2nd century AD, served as a defensive fortification marking the northern boundary of Roman Britain, much further north than Wiltshire. Windsor Castle, while impressive, is a royal residence with a history spanning nearly 1,000 years, but it's a medieval structure, not prehistoric like Stonehenge. So, when you think of ancient mysteries and standing stones in Wiltshire, Stonehenge is the iconic landmark that immediately comes to mind.