Stonehenge is a uniquely fascinating part of our national heritage, a source of mystery and wonder for centuries. It has specially perplexed many scientists, some of whom have deeply pondered the significance of its alignments and numerics. Prominent among them was Gerald Hawkins, pioneer ‘archaeo-astronomer’ whose original ideas, published through his 1965 book Stonehenge Decoded, have stimulated debate and controversy ever since. Sadly, he did not survive to see the publication of this book, co-authored with Hubert Allen. But this finely illustrated text is a fitting memorial to him, and will, as he would surely have hoped, help to introduce a new generation to Stonehenge and its mysteries.