Brought up in the Catholic religion (however loosely), I think first of the altar in church. I guess one is baptized by/at the altar, and receives first holy communion at the altar--both of which I did. Could be wrong, these things maybe don't happen at the altar, I don't remember my Catholicism.
I know I never married at the altar, or anywhere else for that matter.
I've never been too into the idea of having my own pagan altar. I can't contain all my sacred "stuff" to one small area. So, you could say there are touches of altars all over the place. This picture shows the closest I've come to having an altar.
It may be a good idea to make space for one again. The crystals could use a recharging center, as well as myself.