Summer solstice alignments—how many UK stone circles are we actually tracking?

So I've been on a bit of a summer solstice pilgrimage this year, visiting various stone circles and ancient sites across the UK. The precision of the alignments is genuinely staggering. Obviously everyone knows about Stonehenge, but I've visited Castlerigg in the Lake District, Callanish on the Isle of Lewis, and Merry Maidens in Cornwall - all perfectly aligned to sunrise/sunset on midsummer's day.

What's fascinating is how many there are that don't get the same attention. There's a brilliant spreadsheet someone compiled (can't find the link, sorry) that lists over 200 confirmed alignments across Britain and Ireland. But here's my question: do we actually know why? Were these for astronomical observation? Religious ritual? Agricultural calendars?

More are there sites we haven't properly catalogued yet? I'm wondering if some of the alignment data from the 1970s-80s studies needs revisiting with modern equipment. Anyone here done any field research?

Excellent thread. The astronomical knowledge these cultures possessed was extraordinary - whether you believe in ancient astronauts or just give credit to human ingenuity, the mathematics alone is remarkable. I'd argue we've probably missed quite a few sites, especially in Scotland where moorland and forestry obscure ground-level monuments. Would be brilliant to organize a proper mapping project.

Professor of archaeology here (well, retired). The short answer is: we think it was primarily for calendar-keeping and seasonal agriculture, but we don't really know for certain. The solstice alignments are real, the precision is impressive, but whether they had deeper cosmological significance or were just practical timekeeping tools is still debated. Most of us think a bit of both, honestly.

Castlerigg is absolutely stunning. Visited on the actual solstice in 2019 and the sunrise alignment is undeniable. Though I will say, standing there at 4 AM in Lake District rain, surrounded by tourists with mobile phones, kind of kills the mystique a bit.

Are there sites we haven't properly catalogued yet?

Definitely. The Rollright Stones in Oxfordshire, for instance, has alignments that aren't widely publicized. There's also a lot of work being done with LIDAR imaging that's revealing previously unknown earthworks and circles hidden under vegetation. Really exciting stuff.

The thing that bothers me is how many sites have been 'lost' or reoriented by farming/building work over the centuries. We're probably only seeing a fraction of what was there originally. Makes you wonder what the full picture would have looked like.