On the train while passing over Regent's canal through the gritty back lanes of Hackney, I have always gazed in wonder at these mammoth ghostly gas holders that dominate the skyline looking specially magical at sunset. In the 200 years that the UK has been using gas power, the country has got used to the distinctive sight of "gasometers". These gas holders have stored coal gas (town gas) and later natural gas for the UK's urban areas, but now all but a handful are obsolete. These industrial iconic structures are at a risk of demolition.