To this day, bunkers have not lost their relevance. There are still hundreds of thousands of these protective structures in Europe, most of them made from reinforced concrete.

"Secret Bunkers" presents four installations from the mid-19th century up until the middle of World War II. Such as the legendary fortress and bunker of emperor Francis I of Austria in today’s Northern Italy which was never put to the test. In the 1930s, the so-called East Wall was intended to shield Germany’s border against a suspected invasion from its Polish neighbor. However, when the Soviet Army advanced to Berlin in early 1945, its bunkers proved worthless. From 1940 onwards, Britain’s Prime Minister Winston Churchill coordinated the war from a bomb-proof bunkers right in the heart of London. Along the French Atlantic Coast, colossal blocks of steel concrete were erected to provide bunkers for the German U-Boats until, finally, they had to give themselves up.

#bunker #documentary #historydocumentary
----
Further videos on hazards and catastrophes :
┕ Submarines: From Raider to Wolfpack | Documentary | Ep. 01
▸   • Submarines: From Raider to Wolfpack |...  
┕ Submarines: Total War at Sea! | Documentary | Ep. 02
▸   • Submarines: Total War at Sea! | Docum...  
┕Arctic War: Fight for oil and gas | ICE RACE | Full Episode 1
▸   • Arctic War: Fight for oil and gas | I...  
----
Interesting links and sources:
https://en.wikipedia.org/wiki/History...
https://www.britannica.com/technology...
https://www.iwm.org.uk/history/how-br...
https://www.history.com/this-day-in-h...
https://www.historycrunch.com/tanks-i...
https://www.britannica.com/technology...