Viator Exclusive: Early Access to Stonehenge with an Astronomer Guide. Gain early access to Stonehenge on a tour with a professional astronomer who sheds light on the UNESCO World Heritage site and its mystery — it’s a Viator Exclusive available nowhere else. Avoid the crowds by visiting the prehistoric monument in the morning, allowing you to take advantage of great photo ops without the masses. As you stroll around Stonehenge, you’ll learn all about the stone circle, a mystical marvel of ancient architecture. Book and Save 20% Off Viator Exclusive: Early Access to Stonehenge with an Astronomer Guide.