I read that Swindon was once a large railway town, what happened? And was what was demolished of notable size and epicness?
Between 1840 and 1900, the population of Swindon expanded from 2,500 people to 45,000. This was predominately because of the construction of Swindon Works in 1841.
The 1920's saw the works covering 300 acres of land and the employment of 14,000 workers.
During the years that British Rail reigned, the works increasingly diminished in use. Despite this; Swindon was the location for the construction of the final fleet of steam locomotives (Class 9F) in 1960. Crewe Works completing the three quarters, or so, of the total order.
Standardisation of the diesel fleet in the 70's resulted in the withdrawl of the mainstay of Western Region dedicated diesel hydraulic locomotives, such as the Warship, Western and Hymek classes and the transfer of national diesel electric classes such as the Class 47.
Swindon was pretty much reduced to repairs and exam work on shunt engines and the DMU fleet by the first half of the 80's.
In 1985, the 150th anniversary of GWR, it was announced that Swindon Works, by then employing 1,500 workers and using substantially less land, was to close.
I have read in the past, although I don't have it to hand, that it was a choice between Doncaster or Swindon Works for closure. Although I can't say for certain whether this was ever a serious consideration or not.