Saint Barbara was imprisoned by her father in a tower that had no windows. There are probably a number of arguments around the question why he chose to imprison his daughter in a tower that had no windows, and of the possible answers one suggests that he was planning to go away on a business trip and did not trust her to behave while he was gone.
When he returned from his journey Saint Barbara's father discovered that the
tower he'd built to keep his daughter safe from harm had windows. A person might
think that such enterprise on the part of a child would be praised, but no. The
old man was shocked and mortified. Either way your correspondent is thinking of
a tower with windows as the proper tribute to the Patron Saint of Explosives,
and it kind of goes with Saint Barbara's tunnel.