[satori99]

I wasn't sure what you were discussing. Like, what is a fly tower? So I went down a barbican rabbit hole and found this part of a video, where one of the theatre fly techs describes the same thing as you!

https://youtu.be/uDdTUBk-qjo?t=140

[ralfd]

Can’t watch the video. What is a fly tower?

[satori99]

The 'flys' are the enormous curtains and backdrops used in theatre productions. They are raised and lowered to set new scenes in a production. They need a large space to be raised into, above the stage--which is known as a fly tower.