They also allow private visits with full access. It's pretty simple to organise - you have to have 2 or more people and you pay £12 for each adult (£10 if English Heritage or National Trust members).

Every day there are two private visit slots - one in the morning before the monument opens to the public, and one in the evening after it closes.

Up to 26 people are allowed in per slot so if there are only two of you, you might be there alone or you might be there with up to 24 people from other groups who've requested the same slot.

Naturally some days are more popular than others :-) especially around the solstices.

I'm definitely going to request a private visit at some point.

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simon