Phase 3b

An inner oval of bluestones was added, likely composed of stones removed from the initial bluestone double circle of Phase 2. In addition, two concentric circles of pits, known as the Y and Z holes, were added outside the trilithon circle. It has been suggested that these were dug as footings for two additional stone circles, but there is no evidence that they ever held standing stones. It may be that, like the Aubrey holes, they had another purpose.