Rome also was able to use its building prowess for military ends like few other powers.

Examples are Masada and Alesia. How do you assault a military fortress that sits on a shear cliff?

You either build a set a walls all the way around the city and starve it out (Alesia) or you build a giant ramp that is slopes gently enough to get your army and siege engines to the walls of the fortress(Masada).

Also the bridge of Apolonius was a major help in enabling Trajan to invade Dacia.