Which of these is a famous Stone Age site in the United Kingdom?

Stonehenge is the correct answer because it's a prehistoric monument that dates back to the Stone Age, specifically the late Neolithic period around 3000 BC, and the early Bronze Age. It's located in Wiltshire, England, and consists of a ring of standing stones. The construction of Stonehenge happened in several phases over hundreds of years, reflecting the beliefs and engineering capabilities of people living in Britain thousands of years ago. The other options are much more recent. Windsor Castle, for example, has its origins in the 11th century after the Norman invasion. Chequers is a country house that became the official residence of the Prime Minister in the 20th century. Nelson's Column was erected in Trafalgar Square in the 19th century to commemorate Admiral Horatio Nelson. So, while these are all significant landmarks in the UK, they simply don't belong to the same ancient period as Stonehenge. Thinking about the age of the structures is a good way to remember the answer.