There are four types of altars. Wooden altars are the worst type, gold altars are the best type. The metal altars can be created inside each others domain, while the stone and wooden altars cannot. However, you can move a finished altar into another domain. Domains do not cross the cave/above-ground layers, so you can have one domain underground and another on the surface. this can be an easy way to get several types of altars in one spot - create them below ground and push them above as you make them (or vice-versa).
{{Template:Out of Date}} <s>Although metal altars are the best type they do not override the influence of a lesser altar, for example a 50ql stone altar will override a 45ql gold altar, the type of material the altar is made out of does not make the influence stronger or weaker.</s> Influence was changed and needs testing as altars definitely sometimes override influence. Metal altars seem to give gifts and [[potion]] more frequently.
:* [[Wooden altar]]