Plenty for adults and kids alike.

https://www.heritageopendays.org.uk/

Do report back!

Interesting one near me. Anyone who MTBs in the Whitstable area will probably be aware of the Victory Wood nuclear bunker (it’s on one of my regular routes in the area so I’ve ridden past it loads. Normally stop off and sit on it for a spot of lunch actually as there’s a great view of the coast!) Will be open to the public next Sat apparently for only the 3rd time ever officially. Hopefully be something interesting/a bit different, I’ve booked my (free) tickets already!

Wow, that would definitely be worth a look zilog.  This really is a terrific opportunity to see things that aren’t normally open to the public, and in my case things that I didn’t know existed.

So much choice in my county and need to make a plan with shortlist.  Having it over 2 weekends is a bonus.