On deeper Dungeons of Doom levels, when the game randomly places an altar in a room without intending to create a temple, sometimes make the room into an abandoned temple.

Alternate ending where you can settle down in an abandoned temple or possibly just a random altar room and become the priest of the temple permanently. (Creating a bones file where you are now an aligned priest).

Abandoned temples can generate as a special room, or else a room containing a random unattended altar may be converted into an abandoned temple.