The Kingdom of Castile, as led by Rodrigo Diaz de Vivar
Unique Ability:
Defenders of the True Faith
Castile has an exclusive way to achieve victory: to do so, you must capture all cities controlled by the founder of the first religion in the game and remove all traces of that religion from the map. If you are the first civilisation to found a religion, then the victory condition requires the extermination of the second religion. +1 Happiness

per 4 followers of your religion in foreign cities and +4 Local Happiness

every time you capture a city belonging to another religion.
Unique Unit:
Calatravan Knight
The Unique Lancer of the Castilian civilisation. Does not start with the Formation I promotion, but instead starts with the Charge promotion. 5 movement

, up from 4. No combat penalty when defending. +25% combat strength

when fighting a unit built in a city following a differing religion to your own. Upgrades to Cavalry rather than the Anti-Tank Gun.
Unique Building: Alcalá
The Unique Castle of the Castilian civilisation. The Alcalá increases the range

of the city it is built in by 1.