It has a pool of scorched oil surrounded by twelve sycamore trees in a circle. Its location is shown on a petroglyph from the Owl Cave, which also indicates that when Saturn and Jupiter are aligned then the Grove opens to the Black Lodge. Glastonbury Grove is first seen at the end of Episode 27. Not until the final episode of the series, Episode 29, was the place actually called by name, Glastonbury Grove by Agent Cooper.