Visitors have flocked to the RAF Uxbridge bunker in such numbers during a trial period of weekend openings that the experiment is to be extended.
Curator Dan Stirland said: “Our visitor numbers have been really good during the three month trial, so we feel confident they will continue to stay high through July and August.
“Many people who have visited during the original three months have said they want to come back with family and friends and we want to give as many people as possible the opportunity to visit.”
To see the historic site, follow the signs into the base from Vine Lane.
There is plenty of parking and new picnic benches outside.
The bunker is open from 10am to 5pm, with the last admission at 4pm.
NORTHWOOD: A classical violin and piano concert is being performed at St Edmund’s Church in Northwood.
Beethoven’s Sonata No. 10 in G major and Schubert’s Sonata No. 1 in D major will be performed by Peter Gammon and Peter Thomas at the event on June 16.
Tickets, which cost £6 and include refreshments, can be reserved by calling 01923 821 869. The event begins at 3.30pm.