When your clan reaches the top of a castle town-based building chain it may then be possible to construct a legendary building. You can only construct a particular legendary building once, and they cannot be destroyed under any circumstances, only captured. If you are the first to construct one your clan will be awarded a permanent clan traits and its associated effects, as well as the opportunity to recruit heroes. Guard your legendary buildings well, they will quickly become a target for your enemies.
Heroes fight in exactly the same way as other units, but are led by an exceptional exponent of his chosen weapon. There is a hero-type for each of the different weapon disciplines; which one can be recruited depends on the type of legendary building you have constructed. Each hero is joined on the field by an entourage of loyal pupils, much like a general and his bodyguard.