For people from overseas visiting England, or even English people that want to experience something different, the summer solstice is a big draw. For anybody in or near to Salisbury on 20th and 21st June (every year), I strongly recommend a visit to Stonehenge which is a UNESCO World Heritage Site along with it’s neighbour Avebury.
Theories about Stonehenge - Wikipedia, the free encyclopedia

The story of Stonehenge is still not 100% known, there are many theories ranging from an alien landing site to an ancient temple. While some theories hold more weight than others, none have been confirmed to be 100% true yet. However the National Trust (the body that looks after Stonehenge) has allowed for the site to be open each summer solstice,  at the request of druid and other pagan communities. This is to allow the druids to celebrate the sunrise of the longest day, but the opening is not restricted to just druids, over 20,000 people attend the event each year and it really is a great atmosphere. There are acoustic instruments, dancing, hula hooping and just about any other natural form of entertainment you can think of. There are food stalls to cater for all of the hungry attendees and portable toilets around the area. With police and st. John’s ambulance in attendance people will be happy to know that they are safe.  The venue usually opens at 7pm on 20th June and closes at 7am on 21st June. I have been 6 times before and I would strongly recommend this to anybody in the area.

Summer Solstice 2012: Astro-Science & Pagan Ritual | Cierra

a travel blog by Graham Targett
Full story at the ‘bigger than England’  website

U.K Solstice Events offer Stonehenge tours of the Summer Solstice, Winter Solstice, Spring Equinox and Autumn Equinox.

Stonehenge Guided Tours
http://www.StonehengeTours.com