La Ventana ("the window") is one of the largest natural arches in New Mexico, a 25-metre-high opening carved by wind and water out of pale Zuni sandstone on the eastern side of the conservation area. It sits at the foot of a tall sandstone cliff that runs for miles along the edge of the lava beds — the dramatic geological boundary between the volcanic and sedimentary halves of El Malpais.
The arch is reached via a short, well-marked trail of about half a mile, just off Highway 117 south of Grants. Early morning and late afternoon are the moments to come, when low sunlight catches the inside of the arch and turns the sandstone a deep orange. There is a small picnic area at the trailhead. Free, open year-round.