The posts are clustered in three areas, the northeast entrance, the southern entrance and the central area of the henge.
Roughly in line with the ditch the causeway of the northeastern entrance shows evidence of between 7 and 9 rows of posts set along a southwest-northeast alignment, and it has been suggested that they formed setting out lines for the observation of the major and minor northern moonrises, another set of four posts that stood about 15 metres northeast could also have been involved with following the movements of the moon.
There have been many timescales attached to the building of the site although it is generally held to have been completed in three identifiable phases over a 1500 year period starting perhaps around 3000BC.
The exact sequence of these phases and indeed their sub phases has changed over the years as new evidence from excavation has come to light and absolute dating techniques such as radiocarbon C14 have been applied.
The use of posts to form an entrance corridor does seem to occur near the southern entrance through the earthwork.Also during this phase of construction a ring of 56 pits were cut about 5 metres away from the inner edge of the bank.These have been named the 'Aubrey Holes' after their discoverer John Aubrey who originally noticed five circular depressions in 1666 although it was not until the 1920's that their full extent was confirmed and recorded.Excavation of 34 of the Aubrey Holes has revealed that 25 of them contained cremation remains that date from this phase of the site indicating that the holes were still visible features in the landscape.
Fragments of pottery show that these deposits belonged to people associated with the Grooved Ware culture and were mostly found towards the eastern side of the monument, other small pits with cremated remains placed in them have been uncovered in the bottom of the ditch and just within the inside of the bank, again these are nearly all found on the eastern side of the earthwork.However here these sections were then joined together to produce a continuous trench about 7 metres wide and 2 metres deep with a causeway or entrance about 4 metres wide to the south and another of 10 metres wide towards the northeast.