SRD:Detect Secret Doors

You can detect secret doors, compartments, caches, and so forth. Only passages, doors, or openings that have been specifically constructed to escape detection are detected by this spell. The amount of information revealed depends on how long you study a particular area or subject.

1st Round: Presence or absence of secret doors.

2nd Round: Number of secret doors and the location of each. If an aura is outside your line of sight, then you discern its direction but not its exact location.

Each Additional Round: The mechanism or trigger for one particular secret portal closely examined by you. Each round, you can turn to detect secret doors in a new area. The spell can penetrate barriers, but 1 foot of stone, 1 inch of common metal, a thin sheet of lead, or 3 feet of wood or dirt blocks it.