Roman war with the Dacians - art by Giuseppe Rava ~ Of special note is the extra armour the legionaries wear on their arms. This was developed during the Dacian wars to help protect the Romans from the falx, a scythe like weapon the Dacians used with great effect against the Romans' Lorica segmentata armour. It sliced right through!
The Roman Empire made great advancements in transportation through the use of roads. These roads allowed for easier trade and effective travel between cities. Sources: http://en.wikipedia.org/wiki/Roman_roads