On September 15th and 16th certain buildings in Vienna, which are normally not open to the public, may be visited.
https://openhouse-wien.at/en/
Sorry to miss this , it looks fascinating . Writing from Rome .
It is Europe wide, the middle two weeks of September, there may very well be stuff to see in Rome too.
In Rome it was this year in May.
Thanks , Nigel . Will be in Firenze at that point , and will keep an eye out .
@steven
See the schedule: http://www.openhouseworldwide.org/
Wmt 1 , Many thanks for the link . While I won't be in striking distance of any of these this season , I will keep an eye out for the coming season .
Steven, you are welcome.