Explosive charges are placed under the towers
The demolition of the Sellafield site's giant cooling towers on Saturday has marked the end of era in Cumbria.
When the Queen flicked the switch at Calder Hall on 17 October 1956, it was hailed as an "epoch-making" event by then Lord Privy Seal, Richard Butler.
The world's first civilian nuclear power station, on Cumbria's west coast, was built using tools and skills developed for WWII tanks and planes.
Praised as a marvel of British engineering, Calder Hall promised a limitless supply of cheap energy.
But 51 years on, changing attitudes and new technologies have taken their toll.
At 1216 GMT on that day in 1956, Her Majesty pulled the lever which sent electricity from the power station into the National Grid for the first time.
A large "clock" on the wall registered the first energy produced.
Nearby Workington was the first town in the world to receive light, heat and power from nuclear energy.
Richard Hardiman's father was one of a group of specially-recruited engineers who worked on Calder Hall's construction.
An atomic "clock" registered the first generated nuclear power
He remembered the reactor pressure vessels being driven through Egremont in Cumbria on the back of Pickford's lorries.
He said recently: "The reactor vessels could not be any bigger.
"They were cast in a foundry in Scotland to a size that could just squeeze through the streets of Egremont with a couple of inches to spare."
Marjorie Taylor remembers being allowed the day off school. She was at Calder Hall with thousands of onlookers awaiting the Queen's arrival. She still has the invitation.
Interviewed in 2006, she said: "We stood for hours. One woman near us collapsed because she had been so excited to see the Queen that she had left home very early without eating anything. We found a camp chair and a sandwich for her."
The Queen gave her opening speech in the shadow of the plant, where explosives were made for Britain's first atomic bomb, and she gave a timely reminder of the more sinister origins of the technology. She said: "This new power, which has proved itself to be such a terrifying weapon of destruction, is harnessed for the first time for the common good of our community."
The Queen opened Calder Hall in October 1956
At its peak, Calder Hall generated four times as much electricity as it did in 1956, but was still considered small by modern standards.
Much of Britain's weapons grade plutonium was also produced at Calder Hall, for Britain's newly-developed nuclear deterrent.
Calder Hall closed in 2003, after surviving nuclear scares like Three Mile Island and Chernobyl.
The government's Energy White Paper, also published in 2003, described nuclear power as "economically unattractive", and focussed on the potential for renewable energy.
Calder Hall has succumbed to a nationwide decommissioning programme, which will see many of Britain's oldest facilities, including Sellafield itself, shut down by 2023.
But Cumbria's long relationship with nuclear energy is unlikely to end here.
The Nuclear Decommissioning Authority (NDA) is based in the county, and the expertise which saw the transition from Calder Hall to Windscale to Sellafield will probably be used in a new generation of facilities planned for the 21st Century.