Take a day trip to Stonehenge.
Visit Stonehenge.It's a really popular place among tourists so in order to fully enjoy the experience visit it during unpopular tourist hours - early in the morning or late in the evening. Check the open hours before you go (www.stonehenge.co.uk).Stonehenge is fenced in order to protect it from the spontanenous 'souvenier collectors' and stone climbers (and to make a few bucks). You must pay to get in.Take an audio tour. Pick up your walkie talkie thingie at the corner of the souvenier shop. While you're walking along the path around the stone circle you will see numbers on the ground. Punch the number into the device and you may listen the guide tell you interesting things about the stone circle: what it (presumably) was used for, how it was build, myths, etc.While you're there, don't forget to just sit down, chill out and let your mind wander.
