The Heelstone is a lone sarsen stone standing well outside the main circle of rocks, close to the main road. There are lots of articles written on what is believed to be the significance of the heelstone, most to do with astronomy.
It is believed that around 2150 BC, bluestones from the Preseli mountains in Wales were brought here. The huge bluestones, each weighing around 4 tonnes (over 8,800 pounds) were dragged on rollers and sledges, loaded onto rafts, dragged overland again and then back on the water, a journey of 240 miles. Whew! That's a lot of work for a bunch of rocks!
Around 2000 BC, the Sarsen stones are believed to have been brought here from the Marlborough Downs near Avebury, about 25 miles from Stonehenge. These stones are quite a bit larger than the bluestones, the largest is estimated to weigh 50 tonnes, moved by sledges and ropes by an estimated 500-600 men.
Stonehenge is also mentioned within Arthurian legend by Geoffrey of Monmouth. He was a clergyman and one of the major figures in the development of British history. He mixes British legend and his own imagination, connecting literary characters such as Ambrosius Aurelianus, Uther Pendragon, and Constantine III to Stonehedge. According to him, Ambrosius wished to erect a memorial to some 3000 nobles who had died in battle with the Saxons. The nobles were buried at Salisbury, and Ambrosius chose Stonehenge to be their monument. He sent 15,000 knights to Ireland to retrieve the rocks from Mount Killaraus, Ireland where it had been constructed by Giants, who originally brought the stones from Africa. The rocks had healing properties and that is why the Giants were so interested in them.
The knights tried to move the rocks with ropes and force, but failed. He then sent Merlin, the wizard, there who dismantled the stones and sent them over to Britain, near Amesbury, where Stonehenge was rebuilt. According to the legend, Ambrosius was buried within the monument.
Loads of tourists never bother paying for the entrance but simply take photos along the road, outside the fence. I found it just as much fun to take pictures of those mean people who had gone through the trouble of getting here (yes, I heard both Americans and Japanese so they weren't local) yet they were too mean to pay...I'm sure it's annoying that a public monument costs money but hey, English Heritage actually maintains the site and make sure you have information, footpaths and so on.
To their favour, English Heritage do provide free access to the stones themselves at the time of the summer solstice, the night of June 20th, from 2200 to 0900, so that you can hopefully watch the sun rise. It does get very busy however.
If you are unable or unwilling to pay the rather steep admission charge, you can presently park on the nearby lanes for free, and still get a good view through the perimeter fence.
Do it. Go there. See it. And don't get too close and pinch pieces, coz those people ruin it for everyone!