This week, it was revealed that York's Cold War bunker could become a museum. Paul Kirkwood paid a visit.

RAGGED strips of wallpaper hung down the dark, dank corridor as I explored, being careful not to slip on loose floor tiles in one of the rooms.

Three old blue coats hung from pegs, looking likely to stay there until the thread holding them rotted, while on the walls were carefully typewritten notices and a calendar for 1991. Everything was labelled with Dymo tape.

Not until the end of the corridor does the purpose of this somewhat sinister building become fully clear. In the largest of the rooms are maps, charts, stickers and, most tellingly, signs with the words "fall out" on them. I was standing in the operations room of a cold war bunker in York.

For 30 years from 1961 the bunker was the regional headquarters of the Royal Observer Corps whose responsibility it was to report nuclear explosions and monitor radioactive fallout. Now a programme of restoration is about to begin under the guidance of English Heritage which held an open day for the bunker earlier this month.

Tucked away behind a former government building in the suburb of Holgate and largely covered in turf, it is one of the very few surviving command buildings and one of an even smaller group of such buildings that still retains many of its fixtures and fittings.

Three crews of up to 20 people would have been responsible for manning the bunker in the event of nuclear war. To enter they would have walked up an external flight of stairs known as the Aztec Temple.

Having passed through the outer wall - 18 inches thick and made from reinforced concrete - they would have gone into the de-contamination room, mindful of even cleaning behind their nails, before descending the stairs to the lower floor.

It was not a peaceful place. The various generators and air conditioning systems made sure of that. "You had a choice between dry stinking air and wet stinking air," recalled our guide who had served as a volunteer in the Corps, coming up from Doncaster one evening a week for training and at weekends for exercises.

The building's self-containment extended to a 50,000-gallon water tank and its own sewerage system. Crews had to be capable of lasting up to a fortnight before the fall-out of a nuclear attack would have cleared sufficiently for them to go outside again. I could see why the bunker had been designed along the lines of a submarine.

Accommodation was provided in two dormitories with associated toilet and shower facilities. The larger female dormitory contained six two-tier bunks while the smaller, men's dormitory had provision for four giving a total of 20 beds and necessitating a "hot bed" system.

The operations room is on two levels. Staff on the gallery gathered reports from the dozens of underground monitoring posts located throughout the Yorkshire region. This information was then manually signalled along various sightlines down to the lower floor where activity was plotted on charts and giant, etched glass plotting maps with a big red cardboard arrow to indicate wind direction. Messages for the duty controller were passed down from the gallery using a bulldog clip tied on to the end of what looked like a broomstick. The system comes across as a model of largely non-computerised efficiency.

The technical equipment that was used has been removed including the machine for Atomic Weapon Detection and Estimation of Yield - or AWDREY as it was quaintly known. Many items are recoverable, but it is other aspects of the restoration that have been challenging English Heritage and its partners since the structure was made a legally-protected monument considered being of national importance in May 2000.

For instance, should they seek completeness by drawing on artefacts from elsewhere or go all out for authenticity to the extent of using materials that are known to fail? Either way, there could be waxy loo paper in the visitors' toilets according, we were told.

Visiting the bunker and realising the previous existence of so many others really brought home to me the seriousness of the threat of nuclear war that existed during my innocent schooldays. Little did I know what was going on underground. Personally, I find the bunker highly evocative just the way it is now. On the open day I had been back in time in a way that few ever will again.

Updated: 10:30 Saturday, November 02, 2002