Back in the spring, Jan Smigmator's swing band was playing at New York's famous Carnegie Hall.
Now they're playing deep underground in a former Soviet nuclear warhead depot in the Czech Republic called Javor 51, which has been converted into the Atom Museum.
It's deep inside the Brdy Highlands forests which, between 1968 and 1990, was fully under Soviet Army control and no Czech citizen was allowed to go near.
"The acoustics here at the Atom Museum are absolutely superb. We have a great time playing here, and I really like the idea of turning atomic munitions depots around the world into jazz clubs," Jan Smigmator told Euronews.
His concerts are partly intended to make the public more aware of the danger of nuclear weapons, and the venue is just one of twenty-four nuclear depots in Eastern Europe and the only one in the world open for the public.
Scud, Luna and Tochka short-range ballistic missiles were attached to the warheads and were able to launch in two hours and twenty minutes and reach European cities including Munich, Frankfurt and Stuttgart.
During the Cold War, the nuclear arsenals of the nine countries with nuclear capabilities - UK, France, USA, Soviet Union, China, India, Pakistan, South Africa and Israel - were able to destroy the world 18 times over.
"This museum was established to warn future generations about what our fathers and grandfathers went through and to make sure it never happens again,“ Smigmator said.