Interesting facts about the entrance door

The need to protect their homes exists from time immemorial. Historically, in the gland, people have seen something so solid and durable, which can be protected. In the entire history of mankind, the technology of manufacturing door structures, as well as the materials from which they were made, changed many times. We will speak about such ordinary metal entrance doors, but as it turned out with a huge amount of interesting facts and a non-standard history.
Interesting fact number 1: in 2010 in Zurich (Switzerland), archaeologists discovered the front door, which is about 5 thousand years old. Thus, this find is the same age as the British Stonehenge. According to scientists, the door structure has survived to the present day due to the fact that at that time the harsh climatic conditions forced people to build their houses around the lakes, and this required strong wood.
Interesting fact number 2: the oldest wooden door, still in use, is located in Westminster Abbey (UK). It is reliably established that it is made of oak, felled in the 11th century. Thus, the approximate age of the door structure is about 10 centuries.
Interesting facts about the entrance door (5 photos)
Interesting fact number 3: throughout the world, metal entrance doors are divided into 13 security classes. And if the doors of safety class 6-7 are found everywhere in bank vaults, then the door steel system of safety class 13 is only in Fort Knox (USA). Fort Knox is a repository of US gold reserves. The steel product, which reliably guards the gold reserves of the United States of America, weighs 22 tons and is 1 meter thick. It is made of seven layers of steel, and it was boiled using secret technology.
Interesting fact number 4: the highest door in the world is located in the spacecraft shop in Florida (USA). It has a height of 140 meters, and 45 minutes is the approximate time of its closing / opening.
Interesting fact number 5: the most heavy door system is considered to be the metal structure, installed in the Lawrence Laboratory in California. Its weight is about 320 tons, and its thickness is almost 2.5 meters. And although it seems that with such a mass, only remote opening / closing is possible, but thanks to the special door hinges the system also opens manually.
Interesting fact number 6: the fastest closing door products installed in laboratories that work with explosives. In case of danger, they close in 0.3 seconds. Such high speed is provided by nitrogen compressed to 1000 atmospheres.