Sometimes a Hero's Hall must be built in certain places. For example, Thesues' Hall needs to be built by the palace, surrounded by walls and have good appeal. On maps where space is at a premium this can be difficult to accomplish. To get around this, after you have filled the requirements to summon the hero, and while the hero is on his/her way to the city, you can demolish the hall and any of the structures you had to build to meet the requirements. Then, rebuild the hall anywhere that is connected to a road. The hero will not care and will serve your city as usual.