As the title says, I'm having issues finding an alter.

Most games, I try to get a pre-crown before heading into the CoC. It's a little time consuming and maybe a little scummy but it increase my survival rates and is something I do on most games.

Generally, I find an altar in PC, UD or the other early dungeon. This time, no luck. I went to R1, R2 and R3 and found nothing either. By the end of R3, my level was getting a little too high and I was in danger of missing pyramid so I've now done that. By my calculations, I can still get a pre-cown (only two artifacts generated and I'm level 17) but I still need to find an altar.

Any advice?

I'll end by saying that as things stand, I don't need the pre-crown (lots of good loot) but this had become somewhat of an obsession for this game and I'd like to do it regardless.