Purpose Of Metal Pillars...
I live too many hours in an office, so I know I'm quite badly out of touch - but I've noticed repeatedly over the past 6 or 8 years the sudden appearance of large and very tall metal pillars, usually semi-hidden behind railway station fences, or in fenced-off waste-ground, etc - but in some places in the open, on pavement verges too. These things are rock-solid, simple, completely featureless, polished gun-metal grey vertical pillars, a good bit wider than most lampposts, but with absolutely no cables, lights, fixings, devices, working parts, cameras, or anything else at all - simply a very tall, closed, "silent", anonymous metal pillar. I'm sure the overall height is at least 40 feet - much taller than streetlamps - but as they have absolutely no features at all, I think most people simply don't notice them.
To me the most curious feature is that a long way up - about 12 or 15 feet up - the diameter of the thing suddenly widens by about 3 inches all the way round, remaining that secondary diameter the rest of the way up. But on top there is nothing - no antennae, no dishes or receivers, no aerials of any description, no cameras - simply nothing but a large, dark, shiny, silent metal pillar - doing whatever they do in total silence, 24/7, with, as far as I know, no questions ever asked.
What are they, please ?