The summer solstice is here. 

For most, this means watching Glasto on the red button and repeatedly pointing out how unreasonably hot it is. But, for some, the day possesses an altogether more spiritual significance. 

For thousands of years, people have gathered at Stonehenge to catch first glimpse of the sun, which miraculously rises between the two supporting pillars of the Heel Stone on the circle's north-eastern side. The day marks the start of summer and an opportunity to reconnect with ancient spirits - or, in layman’s terms, getting down to Salisbury, smashing a bunch of ketamine and getting stuck right in to a bloody good bongo circle . 

But what is Stonehenge? It’s very existence, not least the methods used to create it, remain amongst the great unsolved mysteries of our ancestry. Many have suggested answers - some more credible than others. Check out the best below.

Aliens 

The biggest stones at Stonehenge are - like - really, really big, with the largest weighing in at around 50 tonnes - about six times the weight of an elephant.

Some people - most notably Erich von Däniken, who wrote the cult book, Chariots of the Gods? - have accordingly reasoned that, along with a number of other megastructures including the pyramids and the Moai heads of Easter Island, Stonehenge must have been created by - or, at the very least, with plenty of help from - a group of God-like aliens from outta space. Problem solved! Next?

Giants

It didn't take long for people to cool down from von Daniken's shock exposé and think: hey, isn't that a little bit presumptuous? Why risk discrediting your argument altogether with reference to extra-terrestrial beings when an equally convincing explanation can be found right under our very noses.

That's right: giants did it. Big, chunky giants called the Nephilim, who allegedly survived Noah's flood by the skin of their teeth, and went on to assist humans in creating a massive stone circle for no particular reason.

Again, some may be worried about the lack of evidence here. But then how do you explain this pic from 1100 AD?

Ancient team-building exercise 

Some historians have pointed to the fact that the stone circle was erected at a time of increased unification of the disparate peoples of Britain - so the build may have effectively functioned as a massive Neolithic team building exercise. 

But, again: for what purpose? Just like the team building exercises of today, it looks like the build would have been gruelling, time-consuming and, in the end, ultimately a complete waste of everybody’s time.