How to Reinforce a Shipping Container to Bury It (EMP Proof)
Other than a full-blown nuclear war, a widespread EMP (electromagnetic pulse) is probably the scariest thing that could happen. You'll want to have plenty of Faraday cages filled with electronic devices, and a shipping container is the ultimate Faraday cage.
Digging a Pirate's Cave - Modern Mechanix (Dec, 1929)
By HI SIBLEY WHILE excavating for a new house in the weed-grown lot next door, workmen unearthed a surprising maze of caves and trenches. Evidently they had been dug many seasons before because bushes and weeds were growing luxuriantly from the soil spread over the roofs. Considerable grading and no end of fancy language were required before the lot was in shape to build on. But it proved that a well-made cave is about as substantial a clubhouse as a boy can make.