Geoff Walden


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Geheimobjekt "Siegfried/Jasmin/Olga/Burg" in the Jonastal

Secret Objects "Siegfried/Jasmin/Olga/Burg" in the Jonas Valley near Ohrdruf

   One of the many Third Reich construction projects that was started but never finished was a series of underground complexes in central Thüringen, southeast of the city of Gotha (near the concentration camp at Ohrdruf, the first such camp found by the Americans on German soil). This project had several code names, depending on what part was meant, and the names also changed over time - the following names were used for all or part of this complex - Siegfried, Jasmin; the designations Olga, Burg, and S/III were sometimes used for the entire project area (including the Jonastal and the surrounding area); "Olga" was also the code name for the "Amt 10" communications center bunker at Ohrdruf. The main works were dug in two sections into a hill forming the north side of the Jonas Valley, between Crawinkel and Arnstadt. This part of the project was reportedly intended as a last-ditch headquarters facility for Hitler and his staff, should they fall back from Berlin into the interior of Germany (some reports say Hitler actually spent the end of March 1945 in this or another nearby underground Führer Headquarters). Other theories say this or a nearby site were intended for production of the intercontinental "Amerika" rocket, and even testing and production of a Nazi atomic bomb. Most of the Jonastal complex never advanced much further than the tunnel digging stage, and the Soviets blasted most of the tunnel entrances after the war. The exact purpose of this facility remains in doubt, as does its code-names ("Siegfried" and "Olga" may actually have been names of other sites).  (Google Maps link)

Please note that this site became part of the adjacent Ohrdruf military training area ca. 2001, and is now posted off-limits to visitors. Bundeswehr authorities take a dim view of trespassing here. The photos shown on this page were taken before the site was posted as off-limits.


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Some 25 tunnel entrances were bored into the hillside overlooking the valley. This site could have provided a very large underground facility.  (panoramic photo from KZ-Gedenkstätte Buchenwald)


This view shows some of the construction activity on the Jonastal hillside, outside the tunnel entrances. Most of the work was done by slave laborers from the concentration camps at Ohrdruf and Buchenwald. The fallen rubble produced when the Soviets blasted the tunnel entrances obscures much of the lower levels today. The entrances to Tunnels 1-12 were in this area.  (Gedenkstätte Buchenwald)


Entrance to Tunnel 12 in 1945. As can be seen, these tunnels were not very large at all, and much work remained to be done before they could be finished. The entrance to Tunnel 12 remains blown up and buried today. (Gedenkstätte Buchenwald)


A large cement mixer was found outside the entrance to Tunnel 15 in 1945. This tunnel entrance is today blocked with masonry and concrete. For some reason, the Soviets did not blast the entrances to Tunnels 13-15. (This entrance was open until ca. 1999. The slit is for bats to fly in and out.)  (Gedenkstätte Buchenwald)


The entrance to Tunnel 14 was also spared from blasting. It is closed today by masonry and a stainless steel gate. (Note - the gate was removed and this entrance was also closed with concrete in 2003.)

The entrances to Tunnels 21 and 22 (with 23 to the right) can be seen under the metal canopy in this 1945 view.  (Gedenkstätte Buchenwald)


Above - Tunnels 1-12 in 1945; below - Tunnels 17 and 18 in 1945.  (Gedenkstätte Buchenwald)


A large bank of air compressors was installed along the valley road near the center of the Jonastal construction site, to power the pneumatic drilling equipment and other air tools.  (Gedenkstätte Buchenwald)


This monument in the Jonastal recalls the victims from the concentration camp S/III at Ohrdruf, many of whom died as slave laborers digging the tunnels for "Siegfried" and "Jasmin."

The Soviets erected this monument near the Jonastal, which commemorates the deaths of over 100 Soviet prisoners of war from the S/III camp at Ohrdruf, who were murdered here by the Nazis in April 1945.


Jonastal webpage  -- 

Jonastal sites  --,

89th Infantry Division liberates Ohrdruf camp  --

Other concentration camp sites  --  Dachau, Buchenwald, Dora (Nordhausen), Sachsenhausen, FlossenbürgMauthausen (includes Gusen), Ebensee (Austria)

Memorial Museums for the Victims of National Socialism in Germany --


   Continue to visit a similar site in Silesia (now in Poland) - Project "Riese" (Giant)

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This page initially uploaded on 20 July 2000.