The unusual sight of Oldbury power station has dominated the banks of the River Severn near Bristol for the past 50 years.
Driving from the nearby town of Thornbury, the power station - which once featured in an episode of Doctor Who - is visible for miles.
The station has reached the end of its life and will generate its last megawatt of electricity on Wednesday.
Last year, reactor two was switched off and now it is the turn of reactor one to be shut down.
The decommissioning of Oldbury - although welcomed by local campaigners - will not be the end for nuclear power generation at the site, with plans for a new station advancing.
Inside Oldbury's tight security cordon, and close to the the station's unusual stripy, cylindrical roof, site director Phil Sprauge explained what will happen during shutdown.
And to stop generating power it really is as simple as pressing an "off" button in the control room.
"The desk operator presses the button... and that press of the button pushes all of the control rods into the reactor which essentially shuts the reactor down," he said.
The man tasked with hitting the off switch is desk operator Andy Freeman who will be watched - via televisions in Oldbury's canteen - by many of the station's 500 staff on Wednesday.
But that is as far as any kind of ceremony goes - no dignitaries have been invited and Mr Freeman just so happens to be the person on shift at the time.
But what will those watching workers think as the final moments come?
"I think most people on-site have been around this idea that it will be closing this calendar year," said Mr Sprauge.
"They have got used to the idea but that's not to say that it won't be tinged with sadness.
"It's been operated extremely well and it's a testament to those people which is the reason you want those people to turn it off as well.
"It'll be a sad day but there's plenty of other things to do."
And it is those "things to do" that will - as electricity generation stops - mark the beginning of the end for Oldbury.
The end, though, will extend many more years into the future than Oldbury's 45-year history.
Over the next three years, all 52,000 fuel elements inside the station's nuclear reactor will be gradually removed which will mean no more heat is generated by the reactor.
The fuel is then taken away - by road from Oldbury to nearby Berkeley, site of another inactive nuclear power station - and then by rail to Sellafield where it is reprocessed.
Once the fuel has gone, other hazards and chemicals on the site such as carbon dioxide, hydrogen and acids are taken away and some of the buildings on the site will be demolished.
"That will probably take about 15 years from now - so in the 2020s," said Mr Sprauge.
"What we will be left with then is the two reactor buildings and the centre block and pretty much nothing else."
The longest job of the entire operation, though, will then begin. Leaving the station to slowly lose its radioactivity.
And that job - which requires little human intervention - will take some 80 long years while the radioactivity from components in the reactor slowly fades.
The final bow for Oldbury's mysterious looking reactor buildings will then come in 2109 when work can begin to pull them down.
By then, the Oldbury reactor buildings may have a new neighbour.
Horizon Nuclear Power - a conglomerate formed by E.On and RWE - hope to build a new power station, next to the existing reactor building, after 2025.
But one resident of nearby Sheperdine - Reg Illingworth - is less than pleased about the idea of a new reactor there.
Mr Illingworth, originally from Liverpool, moved to the nearby village of Shepperdine when plans were afoot to decommission Oldbury in 2007.
But the life of the station was extended until 2012 before plans for the the Oldbury B station were announced.
"I'm hyper, hyper worried," said Mr Illingworth, who is a member of a local anti-nuclear campaign group. He added he was "glad to see it's closing".
Oldbury was originally planned to operate until the end of 2012, but its managers have taken the decision to switch off early - and Mr Illingworth said he was sceptical about that decision.
"I had a meeting with Oldbury site management who said they said they had enough fuel to run to December 2012," he said.
"I think it's not an economic factor but something to do with age."
But Oldbury site boss Mr Sprauge disagreed.
"I think the reason it's the oldest operating civil nuclear power station is that it had been designed properly, it's been looked after properly and it's been operated very well."