Held on June 20, the summer solstice, the event called on people to participate in a sunrise-to-sunset endurance relay, with donors pledging various amounts per hour of participation.

FORBES: Major Alzheimer's Milestones in 2012

Now, although a popular tourist attraction by day, it retains some of its spiritual identity annually on the summer solstice as visitors come from all over the world to experience sunrise together.

UNESCO: UK National Commission for UNESCO - Longest crowds for the longest day, as Stonehenge solstice visitors reach 23,000