Basic Rules (2014) - Modified
1-level Divination
For the duration, you know if there is an aberration, celestial, elemental, fey, fiend, or undead within 30 feet of you, as well as where the creature is located. You also sense whether the hallow spell is active there and, if so, where.
The spell is blocked by 1 foot of stone, dirt, or wood; 1 inch of metal; or a thin sheet of lead.