How did I get the idea to make my own tunnel?
Well, at first it was not my intention.
I was actually planning to make a basement to store all the things that I don't need very often during the year.
Once finished, I would have my own mancave for the room above.
Getting started is not so easy.
First I had to find out how deep I could go, but also how thick my concrete floor is and how real the threat of collapsing walls is.
Information about basements is not so general.
So I expanded my search to include related civil engineering such as well drilling, masonry sewers, tunnels.
And even non-civil engineering such as trench construction and guerrilla warfare.
That's how I stumbled upon this wikipedia page "Tunnelling as a hobby".
It has intrigued me so much that the plans for a basement are now secondary.
At the moment, I have no specific plans for the purpose of this tunnel.
It is fun and challenging.