Obviously, there are gaps in our knowledge of Roman construction techniques and tools because we lack either written or physical evidence of these. Non-permanent materials have eroded away over two millennia and their characteristics elude us. Great structures like Hadrian’s Wall survive because of the use of stone or concrete.
There is, however, one clear example of a non-permanent structure which we know a lot about – Caesar’s first bridge over the Rhine. We know the story because Caesar tells us in volume four of The Conquest of Gaul. But construction techniques are only part of the story. Caesar built this bridge to show the Germans they were never safe from him because he had the skills to cross the river and attack them.