>> If Rome wrote an engineering manual, it would still be quite valid today.

We have some ancient engineering manuals. A book I read, most likely Brotherhood of Kings, remarked that Mesopotamian engineering manuals are primarily concerned with how many bricks will be required for a given structure.

The manuals are valid today, I guess, but useless. We prefer pipelines to brick aqueducts. Our fortresses are made of different materials and need to defend us from different things.