TERMÍNY A VSTUPENKY

RetroTech: A journey into the history of telecommunications

RetroTech: A Journey into the History of Telecommunications is a technical-historical program that will take you to the normally inaccessible areas of the building. It lasts three hours and you will learn about historical communication technologies. We will show you technologies that were used in Czechoslovakia not only during the Cold War. You will be able to try out some functional period technologies yourself.

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RetroTech: A journey into the history of telecommunications

This three-hour program in the Přáslavice bunker represents a unique opportunity to immerse yourself in the history of telecommunications technology and experience how Europe prepared for war in the 1970s. The shelter, fully equipped with period technology , is a place that was key to communication between Berlin and Moscow.

We will show you unique and still functional technologies from the second half of the last century, such as a private branch telephone exchange. You will also see the technologies that were supposed to allow the bunker crew to function even if a nuclear war raged outside.

RetroTech program content: A journey into the history of telecommunications:

  • History of telephone networks in Czechoslovakia, construction of the National Cable Circuit, types of telephone exchanges in Czechoslovakia (local, nodal and transit).
  • Separation of low-frequency and high-frequency signals and their transmission including signal modulation.
  • The principle of the telephone tone generator, so-called callsigns .
  • The principle of creating a telephone connection on the Tesla P51 analog exchange and comparison with our functional CA102 analog exchange.
  • Connection of field telephones via a field exchange and testing of the creation of a telephone connection.
  • Explanation of the principle of the telephone exchange, comparison of the field exchange with the automatic telephone exchange, the principle of the P51 exchange manufactured by Tesla in Czechoslovakia.
  • Undisturbed supply, principle of uninterrupted supply of electricity, ward-leonard set, explanation of phase shift and phase shift.
  • Principle of battery factory, types of batteries and their use, comparison with current technologies.
  • Engine shop, principle of four-stroke internal combustion engine, explanation of the principle of ČKD6S350PN engines, principle of injection pump on ČKD engines.

Explore the largest publicly accessible bunker in Central Europe, dating back to the Cold War period. Enter a space full of history and learn about the telecommunications technologies of the time.

During the intensive three-hour program, you will experience a part of history that has often been neglected in school textbooks. You will immerse yourself in an underground world that fascinates not only enthusiasts of military history and telecommunications technology, but also anyone who desires knowledge and is naturally curious. We offer an experience for all ages, from adults to teenagers.

During the program, you will have enough time to take photos and soak up the authentic atmosphere of the object.

Admission Individuals

Children up to 6 yearsfree
Children from 6 to 15 years450 CZK
Adults590 CZK
Seniors over 65 years450 CZK

Group admission *

RetroTech program for the group (in Czech)

540 CZK / person or 21 EUR / person

The minimum number of people is 10 and the maximum is 25
RetroTech program for the group

600 CZK / person or 25 EUR / person

The minimum number of people is 10 and the maximum is 25
Price for bus tours 40 – 50 people, the tour is divided into 2 groups with the start of the program 15 minutes in a row

480 CZK / person or 20 EUR / person

The minimum number of people is 40

* Group tours are carried out outside the standard public dates. The tour can be customized according to the fitness of the group. For example, for retirement clubs, schools, children’s camps, etc.

Request a tour date

Program information

Duration of the programme180 – 200 min
Maximum number of people on the program / maximum group size25 people or according to the price list
There is no possibility to buy tickets on site. Purchase of tickets only electronically. For groups by agreement. The tour route includes 4 floors, the temperature is 17°C, there are no toilets on the route

RetroTech: A Journey into the History of Telecommunications (Program and Tour)

The tour route is similar to the Extended VIP Tour. However, more space is devoted to the description of technologies and their historical context. During the program, participants can connect and try out some of the period technologies themselves. It is an interactive program during which they will also visit various places that are part of other sightseeing tours.

Places and activities that are not part of the standard tour are highlighted in yellow. You will only see them as part of the RetroTech program.

Decontamination inlet, decontamination airlocks

The decontamination entrance is crucial to ensure the safety and protection of people inside the bunker in the event of a nuclear or chemical attack. Its main function is to remove contaminating particles and substances from the clothing and body surfaces of people entering the bunker to prevent radioactive or toxic material from being introduced inside.
January 01, 2021
12:00 AM

Decontamination preparation and management

In these rooms, solutions for decontamination were prepared. There was a clothing warehouse and the passage of decontamination in the event of a nuclear or chemical attack was controlled from here.
January 01, 2021
12:00 AM

Main staircase with infirmary and morgue

The staircase provides a stunning view of the massiveness of the entire building. The path leads further to the part with the infirmary and morgue.
January 01, 2021
12:00 AM

Amplification Station Operations Manager's Office

Several offices are furnished in the period style, including pictures of landscapes on the walls and false windows. These were supposed to give the crew at least a partial sense of normality in the event of war.
January 01, 2021
12:00 AM

PBX Halls

The central halls were the reason for the construction of the entire bunker. They were of fundamental importance and in the event of war they would ensure communication between the Warsaw Pact countries and communication within the Czechoslovak Republic. In this part of the tour, we will talk about the history of telephone networks in Czechoslovakia, including the construction of the National Cable Circuit. We will look at different types of telephone exchanges. These include local exchanges, which were used to connect local calls directly, nodal exchanges to connect different regional networks, and transit exchanges to transfer calls between different regions.
January 01, 2021
12:00 AM

Telex workplace

We will talk about the functioning of teleprinters and telex technology. We will show how telex works in practice.
January 01, 2021
12:00 AM

MZM switchboard

Here we will demonstrate the technical solution of the MKKM-1 control panel, including the elements that were used on it, and we will show you its topology.
January 01, 2021
12:00 AM

Technology of the original control panel

Here we will talk about the division of low-frequency and high-frequency signals, where these signals are transmitted in different ways, including signal modulation, which is the process of changing the characteristics of the carrier signal according to the information signal. We will show the principle of a telephone tone generator (caller). It is a device capable of generating different tones for different purposes, such as calling, busy lines or other signaling in telephone networks.
January 01, 2021
12:00 AM

Cable chambers

From here, military and civilian lines of communication diverged in different directions. There was also the technology of pressurizing the cables of the K1920 line.
January 01, 2021
12:00 AM

PBX and internal communication management of the building

Here you will see a functional private branch telephone exchange and see how the first automatic call connection took place. There is also a radio control center and the building's internal time. We will show how to create a telephone connection on the Tesla P51 analog PBX and compare it with the CA102 analog PBX. We will talk about the process of routing calls, creating connections and communication between participants using analog technologies. Here you will try connecting field telephones via a field exchange and creating a telephone connection. We will explain the principle of a telephone exchange and compare field exchanges with an automatic telephone exchange.
January 01, 2021
12:00 AM

Dining room, kitchen and bedroom

For the crew, there was a service area with a dining room, bedroom and food storage in the bunker.
January 01, 2021
12:00 AM

Hall undisturbed electricity supply and battery room

Communication was never to be interrupted. Therefore, key technologies have never been powered directly from the grid. In the bunker, there was an ingenious solution with an automatic backup from the battery room. An uninterrupted electricity supply includes the principles of " interference-free supply". We will show the ward-leonard voltage stabilization mechanism and explain phase shift, which is the phase change of an electrical signal.
January 01, 2021
12:00 AM

Army floor with secret police section

A separate floor was reserved for the army detachment and the secret police group.
January 01, 2021
12:00 AM

Encryption and secrecy space

In several halls, telex and voice encryption and secrecy of military communications took place. Broadcasting was also controlled from here through terrestrial antenna arrays, which are located in the bunker area.
January 01, 2021
12:00 AM

Aquaponic farm

The bunker combines old military technology with super modern agricultural technology. On this floor there is a part of the vertical aquaponic farm of the Flenexa company, which can be seen during the tour.
January 01, 2021
12:00 AM

Technological floor with air filtration, boiler room and technological control room

The lowest floor is the technological heart of the bunker. There are air filtration technologies, regime closure of the building and other technologies necessary for survival in the event of a nuclear conflict.
January 01, 2021
12:00 AM

Facilities for the maintenance group and the technological floor

On the lowest floor, there were facilities for the maintenance group of the entire building. We will go through the kitchen, storage, day room and other facilities.
January 01, 2021
12:00 AM

Air Valves and Air Control Section

For both peacetime and war operations, it was necessary to ensure air circulation in large volumes. The air conditioning throughout the building is a technological gem and at this point of the tour we will visit the airlocks and places where it was possible to regulate the air circulation.
January 01, 2021
12:00 AM

ČKD 6S350PN engine technology and backup power supplies

The pride of the building is the functional backup power supplies, which could supply energy to the entire building and all communication technologies for several days. We will explain the principle and construction of ČKD engines, Motorpal injection pumps on ČKD engines and other technical and operational details of such giant engines. This is the last stop of the tour.
January 01, 2021
12:00 AM

Take a look at what it looks like in the bunker

Photo gallery