Stonehenge was indeed a circle.
In a Dutch news article I saw something that I appreciate to learn about.
Because of the drought in the UK, the caretaker of the Stonehenge premises discovered that Stonehenge originally was a full circle, something that many people already suspected. Scientist now say that proof is available.
The simple fact that the garden hose of the caretaker wasn't long enough to water the entire area, certain parts of the grass turned brown. One of the people working there discovered that those dark patches exactly matched the spots where the missing stones had been expected to stand. Even this many years later, the consistency of the ground is still so different that the marks (by changing the way plants grow) are visible to date.
Using a drone, pictures were made from the air in which the entire shape of Stonehenge became visible. Also other marks, like older excavations, were clearly visible through their changed colour. The caretaker now ponders if he should stop watering other parts of the monument at the next drought. Perhaps more things will emerge then.