You can appoint a hero to be a castellan in each of your three cities. The cities then receive a bonus to resource production and building time reduction based on the hero's intelligence. For every 1 point of intelligence you gain 0.25% production and reduce building speed by ___%. To appoint, the hero must be in the desired city. Enter the Senate and select the 'Castellan' tab. Then select the hero and click 'appoint.'