The sophistication, organization, and shear manpower required for even the smallest monuments on the Salisbury Plain of England, not to mention the extreme size and complexity of Stonehenge, dispell all beliefs that they were built by a primitive and barbaric people. It is estimated that there were thirty million manhours of hard labor invested in the construction of stonehenge.

The actual construction of Stonehenge was done in three seperate phases:

Phase I (2950-2900 BC), took place during the Neolithic farming period. It involved the construction of a circular ditch which is enclosed by two earthen banks with two entrances. Inside the inner bank, the fifty-six Aubry Holes named after John Aubrey, the man to first record them, were dug. The circular ditch and the fifty-six Aubry Holes share the same center, which is evidence that these were constructed during the same period.

Phase I (2950-2900 BC)

Phase II (2900-2400 BC), took place during the Middle Neolithic into the Late Neolithic. It involved the construction of the timber monument. The first alteration during the second phase was the intentional filing of the ditch with fresh chalk. Their were also timbers that were constructed at the main northeast entrance, the southern entrance, and in the center. The timbers in the northeast entrance were the most organized and therefore the easiest to interpret. Their placement suggests a series of wooden walls that were parallel to one another and formed corridors, through which the misummer sunrise would have shone. The timbers at the southern entrance are arranged the same way and are thought to have funneled people through a confined space before entering the sacred area within. The timbers in the center are the most confused and therefore the hardest to interpret. They appear to have once formed a circle, but because of fallen stones and earlier excavations the timbers have become unorganized. It is thought that they formed a internal wooden structure similar to that of Woodhenge and Durington Walls, both ancient monuments in England. It is possible that some of the posts were similar to the totem poles of the North American hunter-gatherer groups.

Phase III (2550-1600 BC), took place during the Late Neolithic Period into the Middle Bronze Age. It involved the construction of the stone portion of Stonehenge. Phase III has now been divided into six sub-phases. The first stones erected were the bluestones during the 3i sub-phase. Some believe that they formed a circle. During sub-phase 3ii the bluestones were dismantled and huge blocks of Sarsen stone were erected to form a circle 13 feet high. Inside the large circle, even larger stones were formed into a horseshoe shape. There were five pairs of "trilithon" sarsens with a lintel stone on top of them. They were graduated in height from the outside to the inside of the horseshoe. The tallest being 23 feet in height. The horseshoe opened to the northeast entrance. Some scholars believe that during sub-phase 3iii several dressed bluestones were arranged in the center of the monument. This has not recieved much support, though. During sub-phase 3iv, twenty of the original bluestones were dressed and formed into an oval inside the horseshoe. Another set of bluestones were placed in a circle around the outside of the horseshoe. The alter stone, which is a single free standing stone was placed in the center of the monument during this period. During sub-phase 3v, the oval of bluestones in the center were rearranged to form a horseshoe inside of the larger horseshoe. The final sub-phase, 3vi, involved the digging of two concentric circles of pits, about twenty feet apart, around the entire stone monument. These were possibly for another set of bluestones, but most scholars believe that this step was never completed.

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Phase III (2550-1600 BC)

There are several other significant stones arranged in various places on the monument:

The heel stone is standing in the avenue that travels to the northeast. Scholars believe that there was once a second heel stone adjacent to the current one.

The slaughter stone lies near the northeast avenue entrance. It was used in sacrifices.

The four station stones placed just inside the inner bank form a rectangle that shares the same center as the monument.