Basilica Cisteren

It says there are some extra light shows at night. Check your dates because it is temporarily closed, but they say there is a different cistern you can tour instead (i didn’t see that one).
https://yerebatan.com/en/
https://cisternoftheodosius.com/

We thought the Basilica Cistern was pricey. It was interesting to visit, and we enjoyed the history and structure and secondarily the art. While we liked it, it certainly would be lower on the list than the mosques, Topaki Palace, etc. We visited during the day. We would not have paid the additional cost to go at night.

I went to the Theodosius cistern because the Basilica was closed when I was there. It has a light show all the time I believe. It was interesting but not a highlight of my Istanbul time.

There is no need to go Basilica Cistern at night. Its underground and has the same lightning all the time.

I wouldn't pay to go at night. I visited it during the day and didn't need a light show to enjoy it.

Thanks everyone!