The exhibition gives people the chance to get up close to machines that changed the world. Muzeum Inżynierii Miejskiej w Krakowie/Facebook

Several dozen historical machines for sending secret information will go on show for the first time in Kraków on Saturday at the city’s Museum of Municipal Engineering.

Entitled 'Warning! Enemies are listening', the exhibition aims to bring the history of cryptography home to the public.

"We wanted to visualise for our guests that cryptography from the Second World War is not just about the Enigma machine. Many other ciphering systems were used," exhibition curator Marek Więcek explained to PAP.

“We wanted to visualise for our guests that cryptography from the Second World War is not just about the Enigma machine,” exhibition curator Marek Więcek explained to PAP.Muzeum Inżynierii Miejskiej w Krakowie/Facebook

On display are several dozen machines that once transmitted secret information, and were used by the likes of the armed forces, the intelligence service and the democratic opposition. The oldest come from the turn of the 19th and 20th centuries. Among the exhibits are tele-printers and field telephones, the history of some of which are related to the legendary Enigma machine.

Among the most valuable objects, which could use information encoded by the Enigma machine, are the field equipment of the Hella telegraphic system used by the German army and the HRO radio receiver produced by the Americans. Both of these rare and historic devices are the property of the Museum of Municipal Engineering.

Among the most valuable objects, which could use information encoded by the Enigma machine, are the field equipment of the Hella telegraphic system used by the German army and the HRO radio receiver produced by the Americans.Muzeum Inżynierii Miejskiej w Krakowie/Facebook

Right at the entrance of the exhibition is an interactive station where visitor can find a tele-printer produced in Czechoslovakia in the 1970s. Thanks to a special system created by staff at the museum, the tele-printer prints the contents of SMS text messages sent to a number provided by the museum.

The 'Warning! Enemies are listening' exhibition runs until January 2020.