Knowledge is worthless without application. To this end, Civic Centre research must be made manifest in projects which improve the quality of your civilisation, which are the various upgrades you find in various non-Civic Centre buildings.
Unlike vanilla Rise of Nations , the tech upgrades of Kings & Conquerors, while retaining their original locations, have different cost structures and prerequisite technologies, with relations meant to reflect real life developments. For instance, in order to ensure proper supply and military might, you will need to first spend time maxing out your agronomic research at the Granary. Once you achieve all three levels, you can then research Supply Depots, which then in turn unlocks the ability to improve your Forts and Fortresses to better withstand enemy attacks.
Also note that not every faction enjoys the same technologies. By far Rome is the most technologically advanced, while others such as the Suebi and Sarmatians are fairly backward.
"The hooves of the horses had been worn thin by steady marching. The arms and armour were wearing out, and the Greek clothing was quite gone. They had to clothe themselves in materials of the barbarians ..." — Diodorus Siculus
You suffer 100% less attrition damage while in enemy territory and none while not moving or fighting.
Ships, Siege and Vehicles production speed increased,
Supply wagon radius, Speed and Hit points increased to level 3.