An at-risk World War II building which was used to train anti-aircraft gunners will now be saved thanks to grants from the lottery and English Heritage.
The Langham Dome in North Norfolk, one of only six training domes in the country, was built in 1942 and sits on the edge of a former RAF base.
Film of enemy planes was projected on its walls to simulate target practise.
It is being restored thanks to £200,00 from English Heritage and £426,000 from the Heritage Lottery Fund.
Once renovations are completed, the dome will open to the public as an education centre.
John Ette, from English Heritage, said the concrete used to build it had suffered severe decay.
The metal rod and mesh sub-structure was also decaying.
"It's required an absolutely innovative technique to run a current through it to drive the moisture out," said Mr Ette.
"Then it has to be refaced, so it's actually quite a technically difficult job and it's taken years to build up the right expertise."
Patrick Allen, from the Friends of Langham Dome - the organisation instrumental in securing the grants for the dome's restoration - said it was the culmination of 20 years' work.
"Future generations can come in here and hopefully will be able to learn what went on in 1940 to 45 in Langham," he said.
"Langham went from a village of 200 people to 2,000 people living here during the war, so it was quite an upheaval for the village.
"I think it's important to remember this," added Mr Allen.