ChatGPT says it's a gasholder (or gasometer) used to store manufactured gas, prior to the adoption of natural gas in the late 1960s–70s. The outer framework supported a telescoping inner tank that would rise and fall depending on the volume of gas stored. Many have since been demolished.
A mystery solved. I wonder if there are any left?
From what I read, there are many across Europe. Some have become listed buildings, or they’ve been remodeled. In Germany one is an planetarium while in Vienna (pictured) they are now apartments!
Thank you for the info. A puzzle solved.
Glad you called my attention to them so I could finally find out about them.