The Heel or Hele stone stands to the northeast of the Stonehenge circles.

The name is probably derived from the Greek word for the sun - 'Helios'.  

Unlike earlier stone circles oriented on natural features like prominent hills, Stonehenge aligns with no natural features all the alignments being man-made. The builders had to provide an outlier to mark the rising of the sun at midsummer as seen from the centre of the circle.

The Hele stone.