The Ada programming language. We (at my work) have been considering it for a new project and mostly everything has been a pleasant surprise. It is not a language that makes you feel “clever” or “powerful”, but everything has its purpose and place.

Except for Tasks; the fact that such a bare-bones language has first-class support for concurrent execution makes it clear how ahead of its time it was.

Another technology was optics and specifically fiber optics. I went into the field with knowledge of microwave engineering and I am surprised by how similar it is. I thought it would be a completely foreign, but the high level concepts are actually relatable to microwave tech.