1, used to regulate feng shui. Used to kill monsters, evil spirits, floods and natural disasters.
2, used to commemorate. Commemorate heroes, martyrs, important days and events.
3, used as a sacrifice. Sacrifice to God and Mother Earth, pray for rain and pray for victory before the war.
And:
4. The image of a city.
Yan 'an Pagoda, one is to ward off evil spirits, and the other is to commemorate the clavicle bodhisattva.