The Cirencester Gas Works, built in 1833 alongside the Thames and Severn Canal, once occupied this site in Bridges Road. Nothing remains today apart from this rather striking round building which used to be the manager's house. Once upon a time it stood in open fields; nowadays it is next to the CDC Highways Depot, with its salt store. I think the Council used to own it, but it looks to me like it is now a private house.
Here it is in an old photography from David & Linda Viner's
Cirencester Through Time (2009)
References:
Bridge End House on British Listed Buildings
If you are interested in that sort of thing, here is an article on the early days of the gas industry in the South West in
The Historic Gas Times.
Extract from K.J. Beecham's History of Cirencester, published in 1886: