Back in the 50s, my great grandfather built the house where my mother and my grandmother grew up in all by himself. It took him 6 years, but he had no help. He started digging into the ground with a shovel. He was a carpenter and bricklayer and used his spare time and skill to do it. This house is still standing and my grandmother still lives in it.
This is him with his wife, my great grandmother: https://i.imgur.com/y7sXvaa.jpg
It was his greatest achievement. But unfortunately he only lived in it for a meager year before passing away.