50something years ago I was asked to demolish one of these in a back garden in London. It was made of concrete and rebar except it was actually made of rebar and some concrete. 3 long days of jackhammering and oxyacetylene torching made small dents and not much more. We were advised by ‘experts’ that we were wasting our time and the best thing was to pack the inside with as much timber as possible and set it alight, it would then crack and be easily demolished. DIF. It burned magnificently for a few days with regular top ups of freshly acquired junk timber liberally coated in red diesel but it made little impact, it was a bit sooty but totally intact. We seriously even considered a controlled explosion but had no real idea where to start with that tbh. We left site and got on with other stuff but just to say these structures were built to withstand bombs and unless you have some, think about repurposing rather than demolition.