They give tours in summer months, but you have to inquire on off months to possibly get one. There were only 4 of us and I first inquired back in February 2024 about having a tour in September. I ended up in contact with the executive director of the foundation which now owns the church. He arranged a time for us to show up and that it would cost $20 a person to get an hour tour.
When we showed up, it turned out they were having generator problems and we would have to tour the Cathedral in the dark. But it was only for a few minutes and then the lights came back on. The executive director was the one who gave us the tour which turned out to be almost hours long. He showed us all over the interior and we were all very impressed with his abundant knowledge of the history of such a beautiful building. He even played one of the two organs for us. We ended up donation $25 a person for the tour. It was well worth it.
By the way, my friend's husband hadn't been eager to take the tour, but by the time we finished, he was very happy we had come.