The Legion is the Roman replacement for the Swordsman. Its strength is greater than either the Swordsman or the Pikeman (which becomes available later), but what's even more interesting about Legions is their ability to build roads and Forts, serving as extra Workers exactly at the time your young empire needs to build its road network. This can be very useful for making city connections to newly captured cities, or building bridges over rivers to allow for faster troop movement across them (much like how Trajan crossed the Danube). You can use your Legions for this purpose any time they aren't fighting, and free up your Workers to build other improvements.
Unfortunately, this unique trait does not extend through upgrades, unlike many other unique traits, and a Legion cannot build on a tile if a Worker is already building something there.
Even after Steel has been researched, the Romans are actually still able to produce Legions. This is unlike most other unique units, which become obsolete with a certain technology similar to the regular ones and are subsequently replaced by their upgrades.
Luckily, even if you're not Rome, you can still get the Legion by being allies with Militaristic City-States (provided Rome is not one of the civilizations in the game).
The Roman Legion is - justifiably - the most famous military unit from antiquity. Armed with a "pilum" (throwing spear) and "gladius" (short sword), and wearing a metal helmet, cuirass and shield, Roman Legions conquered the known world. Along with the best weapons technology available at the time, the Roman Legions were highly trained and extremely disciplined. Under competent leadership there was literally no other military able to stand up to them.
- One of the advanced techniques learned by Roman Legions was the testudo or tortoise formation, which would shield them from incoming archery attacks.
- Roman Legions were very effective in the Roman wars with the Gallic tribes due to their better organization, training, and general disunity of the Gallic tribes.