Detect Dragons

For the duration, you know if there are any dragons and other draconic creatures within 30 feet of you, as well as where the creature is located, regardless of any disguises or transmutation magic. If you spend 1-minute concentrating on a dragon, you learn the dragon's age and type.  

The spell can penetrate most barriers, but is blocked by 1 foot of stone, 1 inch of common metal, a thing sheet of lead, or 3 feet of wood or dirt.