Re: Open House London
"If they opened on different days throughout the year, more people would be able to visit each place!"
I don't think that's true.
The number of people who could visit a building is unaffected by the number of other buildings that are open.
The number of people who want to visit a building is arguably increased by having a special open house weekend which is publicised https://openhouselondon.open-city.org.uk and which people plan to go to every year. I've been going for 20+ years and I've seen some fascinating places.
Biting the hand that feeds IT
